Cardiovascular Testing Detects Underlying Dysfunction in Childhood Leukemia Survivors
01-03-2020 – LONG, TREYA M.; LEE, FELICITY; LAM, KAITLYN; WALLMAN, KAREN E.; WALWYN, THOMAS S.; CHOONG, CATHERINE S.; NAYLOR, LOUISE H.
Purpose Childhood leukemia survivors commonly develop late-onset cardiovascular disease after treatment with anthracyclines. Resting echocardiogram is the standard procedure for monitoring cardiac health but this method may not be sensitive enough to detect subclinical injury. Exercise echocardiography may provide a viable alternative.
Methods Nineteen (9 males; age, 19 ± 3 yr) anthracycline-treated survivors of childhood leukemia and 17 (8 males) healthy individuals of similar age (22 ± 2 yr) were recruited. All survivors had normal resting echocardiography upon recruitment. Exercise echocardiography was performed using contemporary imaging techniques. Flow-mediated dilation (FMD), body composition, and cardiorespiratory fitness (V˙O2peak) were assessed to determine predisposition to additional disease.
Results Mitral valve peak flow velocity in late diastole (interaction, P = 0.007) increased from rest in survivors (P = 0.023) and controls (P = 0.020) immediately postexercise but did not recover again in the survivors (exercise-recovery, P = 0.784) after recuperation. Consequently, E/A ratio (interaction, P < 0.001) was lower in the survivors at recovery (P < 0.001). Survivors had reduced FMD (7.88 ± 1.70 vs 9.65 ± 2.83; P = 0.030), maximal and recovery HR (P = 0.001; P < 0.001), minute ventilation (P < 0.001), and V˙O2peak (absolute, 2.64 ± 0.62 vs 3.14 ± 0.74 L·min−1, P = 0.034; relative, 36.78 ± 11.49 vs 45.14 ± 6.80 m
L·kg−1·min−1; P = 0.013) compared with controls. They also had higher total body fat (percentage, P = 0.034; mass, P = 0.024) and fat mass in the central (P = 0.050), peripheral (P = 0.039) and visceral (P < 0.001) regions. Survivors matched controls with regard to height (173.0 ± 7.8 cm vs 173.8 ± 9.1 cm; P = 0.796), body mass (76.16 ± 19.05 kg vs 70.07 ± 13.96 kg; P = 0.287) and body mass index (25.2 ± 5.1 vs 22.9 ± 2.7; P = 0.109).
Conclusions Exercise echocardiography unmasked subclinical diastolic dysfunction that may indicate late anthracycline toxicity in apparently healthy survivors of childhood leukemia. Presence of secondary risk factors indicates increased predisposition to comorbidities and highlights the importance of assessing cardiovascular health during follow-up.
Dysregulated Inflammatory Response Related to Cartilage Degradation after ACL Injury
01-03-2020 – JACOBS, CALE A.; HUNT, EMILY R.; CONLEY, CAITLIN E.-W.; JOHNSON, DARREN L.; STONE, AUSTIN V.; HUEBNER, JANET L.; KRAUS, VIRGINIA B.; LATTERMANN, CHRISTIAN
Purpose Elevated synovial fluid (SF) concentrations of proinflammatory cytokines, degradative enzymes, and cartilage breakdown markers at the time of anterior cruciate ligament (ACL) reconstruction are associated with worse postoperative patient-reported outcomes and cartilage quality. However, it remains unclear if this is due to a more robust or dysregulated inflammatory response or is a function of a more severe injury. The objective of this study was to evaluate the association of the molecular composition of the SF, patient demographics, and injury characteristics to cartilage degradation after acute ACL injury.
Methods We performed a cluster analysis of SF concentrations of proinflammatory and anti-inflammatory cytokines, and biomarkers of cartilage degradation, bony remodeling, and hemarthrosis. We evaluated the association of biomarker clusters with patient demographics, days between injury, Visual Analogue Scale pain, SF aspirate volumes, and bone bruise volumes measured on magnetic resonance imaging.
Results Two clusters were identified from the 35 patients included in this analysis, dysregulated inflammation and low inflammation. The dysregulated inflammation cluster consisted of 10 patients and demonstrated significantly greater concentrations of biomarkers of cartilage degradation (P < 0.05) as well as a lower ratio of anti-inflammatory to proinflammatory cytokines (P = 0.053) when compared with the low inflammation cluster. Patient demographics, bone bruise volumes, SF aspirate volumes, pain, and concomitant injuries did not differ between clusters.
Conclusions A subset of patients exhibited dysregulation of the inflammatory response after acute ACL injury which may increase the risk of posttraumatic osteoarthritis. This response does not appear to be a function of injury severity.
Clinical and Device-based Metrics of Gait and Balance in Diagnosing Youth Concussion
01-03-2020 – CORWIN, DANIEL J.; MCDONALD, CATHERINE C.; ARBOGAST, KRISTY B.; MOHAMMED, FAIRUZ N.; METZGER, KRISTINA B.; PFEIFFER, MELISSA R.; PATTON, DECLAN A.; HUBER, COLIN M.; MARGULIES, SUSAN S.; GRADY, MATTHEW F.; MASTER, CHRISTINA L.
Purpose Evaluate the discriminatory ability of two clinical measures and one device-based measure of gait and balance for concussed youth.
Methods We enrolled 81 cases and 90 controls age 14–18 yr old from August 2017 to June 2018. Controls were recruited from a suburban high school, and cases were recruited from the concussion program of an academic pediatric tertiary care center. Tests included two clinical measures: 1) complex tandem gait, scored as sway/errors walking forward and backward eyes open and closed; 2) Modified Balance Error Scoring System (m
BESS), scored as total number of errors on three standing tasks; and one device-based measure; 3) Modified Clinical Test of Sensory Interaction and Balance (m
CTSIB) using the Biodex Biosway Balance System, scored as a sway index. Sensitivity, specificity, ideal cutpoint, and area under the receiver operating characteristic curve (AUC) were calculated for all test components.
Results Ideal cutpoint for total number of sway/errors for tandem gait = 5, sensitivity 41%, specificity 90%. Ideal cutpoint for total m
BESS errors = 4, sensitivity 55%, specificity 75%. Ideal cutpoint for m
CTSIB = 1.37, sensitivity 37%, specificity 88%. Among each test, some individual components outperformed overall composites, in particular tandem gait (specificity forward eyes open = 99%, sensitivity backward eyes closed = 81%). Among the 40 cases and 65 controls with all three assessments, AUC (95% CI) for tandem gait = 0.63 (0.52,0.75), m
BESS = 0.70 (0.60,0.81), and m
CTSIB = 0.54 (0.42,0.66).
Conclusions A device-based measure of balance did not produce better discriminatory ability than two clinical assessments. Complex tandem gait has the additional benefit of being an easy-to-perform and graded test with highly sensitive and specific individual components.
Age-related Deficits in Voluntary Activation: A Systematic Review and Meta-analysis
01-03-2020 – ROZAND, VIANNEY; SUNDBERG, CHRISTOPHER W.; HUNTER, SANDRA K.; SMITH, ASHLEIGH E.
Whether there are age-related differences in neural drive during maximal effort contractions is not clear. This review determined the effect of age on voluntary activation during maximal voluntary isometric contractions. The literature was systematically reviewed for studies reporting voluntary activation quantified with the interpolated twitch technique (ITT) or central activation ratio (CAR) during isometric contractions in young (18–35 yr) and old adults (>60 yr; mean, ≥65 yr). Of the 2697 articles identified, 54 were eligible for inclusion in the meta-analysis. Voluntary activation was assessed with electrical stimulation and transcranial magnetic stimulation on five different muscle groups. Random-effects meta-analysis revealed lower activation in old compared with young adults (d = −0.45; 95% confidence interval, −0.62 to −0.29; P < 0.001), with moderate heterogeneity (52.4%). To uncover the sources of heterogeneity, subgroup analyses were conducted for muscle group, calculation method (ITT or CAR), and stimulation type (electrical stimulation or transcranial magnetic stimulation) and number (single, paired, or train stimulations). The age-related reduction in voluntary activation occurred for all muscle groups investigated except the ankle dorsiflexors. Both ITT and CAR demonstrated an age-related reduction in voluntary activation of the elbow flexors, knee extensors, and plantar flexors. ITT performed with paired and train stimulations showed lower activation for old than young adults, with no age difference for the single electrical stimulation. Together, the meta-analysis revealed that healthy older adults have a reduced capacity to activate some upper and lower limb muscles during maximal voluntary isometric contractions; however, the effect was modest and best assessed with at least paired stimulations to detect the difference.
Cognitive Impairment during High-Intensity Exercise: Influence of Cerebral Blood Flow
01-03-2020 – KOMIYAMA, TAKAAKI; TANOUE, YUKIYA; SUDO, MIZUKI; COSTELLO, JOSEPH T.; UEHARA, YOSHINARI; HIGAKI, YASUKI; ANDO, SOICHI
Purpose Cognitive performance appears to be impaired during high-intensity exercise, and this occurs concurrently with a reduction in cerebral blood flow (CBF). However, it is unclear whether cognitive impairment during high-intensity exercise is associated with reduced CBF. We tested the hypothesis that a reduction in CBF is responsible for impaired cognitive performance during high-intensity exercise.
Methods Using a randomized crossover design 17 healthy males performed spatial delayed response and Go/No-Go tasks in three conditions (exercise EX, exercise+CO2 EX+CO2, and a nonexercising control CON). In the EX and EX+CO2, they performed cognitive tasks at rest and during 8 min of moderate and high-intensity exercise. Exercise intensity corresponded to ~50% (moderate) and ~80% (high) of peak oxygen uptake. In the EX+CO2, the participants inspired hypercapnic gas (2% CO2) during high-intensity exercise. In the CON, they performed the cognitive tasks without exercise.
Results Middle cerebral artery mean velocity increased during high-intensity exercise in the EX+CO2 relative to the EX (69.4 10.6 cm·s−1, vs 57.2 7.7 cm·s−1, P 0.10). These results demonstrate that restored CBF did not prevent cognitive impairment during high-intensity exercise.
Conclusions We conclude that a reduction in CBF is not responsible for impaired cognitive performance during high-intensity exercise.
Diet and Exercise Training Influence Skeletal Muscle Long-Chain acyl-CoA Synthetases
01-03-2020 – STIERWALT, HARRISON D.; EHRLICHER, SARAH E.; ROBINSON, MATTHEW M.; NEWSOM, SEAN A.
Introduction Long-chain acyl-Co
A synthetases (ACSL) are implicated as regulators of oxidation and storage of fatty acids within skeletal muscle; however, to what extent diet and exercise alter skeletal muscle ACSL remains poorly understood.
Purpose This study aimed to determine the effects of diet and exercise training on skeletal muscle ACSL and to examine relationships between ACSL1 and ACSL6 and fat oxidation and fat storage, respectively.
Methods Male C57BL/6J mice consumed a 60% high-fat diet (HFD) for 12 wk to induce obesity compared with low-fat diet (LFD). At week 4, mice began aerobic exercise (EX-Tr) or remained sedentary (SED) for 8 wk. At week 12, the protein abundance of five known ACSL isoforms and m
RNA expression for ACSL1 and ACSL6 were measured in gastrocnemius muscle, as was skeletal muscle lipid content. Fat oxidation was measured using metabolic cage indirect calorimetry at week 10.
Results Of the five known ACSL isoforms, four were detected at the protein level. HFD resulted in greater, yet nonsignificant, ACSL1 protein abundance (+18%, P = 0.13 vs LFD), greater ACSL6 (+107%, P < 0.01 vs LFD), and no difference in ACSL4 or ACSL5. Exercise training resulted in greater ACSL6 protein abundance in LFD mice (P = 0.05 LFD EX-Tr vs SED), whereas ACSL4 was lower after exercise training compared with sedentary, regardless of diet. Under fasted conditions, skeletal muscle ACSL1 protein abundance was not related to measures of whole-body fat oxidation. Conversely, skeletal muscle ACSL6 protein abundance was positively correlated with intramyocellular lipid content (P < 0.01, r2 = 0.22).
Conclusion We present evidence that ACSL isoforms 1, 4, and 6 may undergo regulation by HFD and/or exercise training. We further conclude that increased skeletal muscle ACSL6 may facilitate increased intramyocellular fat storage during HFD-induced obesity.
Cachexia Disrupts Diurnal Regulation of Activity, Feeding, and Muscle Mechanistic Target of Rapamycin Complex 1 in Mice
01-03-2020 – COUNTS, BRITTANY R.; HARDEE, JUSTIN P.; FIX, DENNIS K.; VANDERVEEN, BRANDON N.; MONTALVO, RYAN N.; CARSON, JAMES A.
Introduction Cancer cachexia is characterized by severe skeletal muscle mass loss, which is driven by decreased muscle protein synthesis and increased protein degradation. Daily physical activity and feeding behaviors exhibit diurnal fluctuations in mice that can impact the systemic environment and skeletal muscle signaling.
Purpose We investigated the effect of cancer cachexia on the diurnal regulation of feeding, physical activity, and skeletal muscle mechanistic target of rapamycin complex 1 (m
TORC1) signaling in tumor-bearing mice. We also examined the impact of increased physical activity on diurnal behaviors and skeletal muscle m
TROC1 signaling in the cancer environment.
Methods Physical activity and feeding behaviors were measured for four consecutive days before sacrifice in male C57BL/6 (B6; n = 24) and Apc
Min/+ (MIN; n = 22) mice at 7:00 AM and 7:00 PM under ad libitum condition. A subset of B6 (n = 16) and MIN (n = 19) mice were given wheel access for 2 wk before diurnal behavior measurements. Gastrocnemius muscle protein expression was examined.
Results The MIN mice demonstrated altered diurnal fluctuations in feeding and activity compared with the B6. Interestingly, cachexia did not alter MIN total food intake, but dramatically reduced cage physical activity. As a measurement of m
TORC1 activity, 4E-BP1 phosphorylation increased after the dark cycle in B6 and precachectic MIN mice, whereas rp
S6 phosphorylation was only increased after the dark cycle in MIN mice. MIN 4E-BP1 phosphorylation at the end of the light cycle was significantly correlated with cachexia progression and reduced physical activity. Voluntary wheel running increased light cycle MIN 4E-BP1 phosphorylation and attenuated muscle mass loss.
Conclusions The cancer environment can alter diurnal feeding and physical activity behaviors in tumor-bearing mice, which are linked to the progression of cachexia and muscle wasting. Furthermore, suppressed physical activity during cachexia is associated with decreased skeletal muscle m
Chicken and the Egg: Physical Activity and Epigenetics
01-03-2020 – LIGHTFOOT, J. TIMOTHY
No abstract available
Physical Activity and Genome-wide DNA Methylation: The REgistre GIroní del COR Study
01-03-2020 – FERNÁNDEZ-SANLÉS, ALBA; SAYOLS-BAIXERAS, SERGI; CASTRO DE MOURA, MANUEL; ESTELLER, MANEL; SUBIRANA, ISAAC; TORRES-CUEVAS, SEBASTIÁN; PÉREZ-FERNÁNDEZ, SILVIA; ASLIBEKYAN, STELLA; MARRUGAT, JAUME; ELOSUA, ROBERTO
Introduction DNA methylation may be one of the biological mechanisms underlying the health benefits of physical activity (PA). Our objective was to determine the association between PA and genome-wide DNA methylation at Cp
Methods We designed a two-stage epigenome wide association study. In the discovery stage, we used 619 individuals from the REgistre GIroní del COR cohort. Next, we validated the Cp
G suggestively associated with PA (P < 10−5) in two independent populations (n = 1735 and 190, respectively). Physical activity was assessed with validated questionnaires and classified as light PA (LPA), moderate PA, vigorous PA, moderate-vigorous PA (MVPA) and total PA. We examined linear and nonlinear associations and meta-analyzed the results in the three populations. The linear associations were meta-analyzed with a fixed-effects model and the P values of the nonlinear associations with the Stouffer and Fisher methods. We established a P value threshold that fulfilled Bonferroni criteria over the number of Cp
G analyzed (0.05/421,940 = 1.185 × 10−7).
Results In the meta-analyses, two Cp
G sites had a statistically significant nonlinear association with MVPA. cg24155427 (P = 1.19 × 10−9), located in an intergenic region in chromosome 1, has been previously associated with smoking, lupus, and aging. cg09565397 (P = 1.59 × 10−7), located within DGAT1 in chromosome 8, which encodes an enzyme involved in triacylglycerol synthesis.
Conclusions This population-based study identified two new, differentially methylated Cp
G sites with a nonlinear dose–response relationship to MVPA. These associations must be additionally validated and may be considered for further research on the biological mechanisms underlying health benefits of PA.
Accelerometer-measured Physical Activity, Reproductive Hormones, and DNA Methylation
01-03-2020 – WU, YUE; GOODRICH, JACLYN M.; DOLINOY, DANA C.; SÁNCHEZ, BRISA N.; RUIZ-NARVÁEZ, EDWARD A.; BANKER, MARGARET; CANTORAL, ALEJANDRA; MERCADO-GARCIA, ADRIANA; TÉLLEZ-ROJO, MARTHA M.; PETERSON, KAREN E.
Introduction/Purpose Limited studies have examined the association of physical activity with reproductive hormones, DNA methylation, and pubertal status among adolescents.
Methods Among 248 boys and 271 girls, we estimated daily physical activity levels based on 7 d of wrist-worn accelerometer data. We used an isotemporal substitution paradigm and sex-stratified regression models to examine the association of physical activity levels with 1) testosterone, cortisol, progesterone, and androstenedione concentrations; 2) DNA methylation of long interspersed nucleotide (LINE-1) repeats and the genes H19, hydroxysteroid (11-Beta) dehydrogenase 2 (HSD11B2), and peroxisome proliferator-activated receptor alpha (PPARA) from blood leukocytes; and 3) Tanner stages, adjusted for age, BMI, and socioeconomic status.
Results In boys, substituting 30 min of moderate physical activity for 30 min of sedentary behavior per day was associated with 29% (−49%, 0%) of lower testosterone and 29% (4%, 61%) of higher progesterone. Substituting 30 min of light physical activity for sedentary behavior was associated with 13% (−22%, −2%) of lower progesterone. Among girls, 30 min of additional sedentary behavior was associated with 8% (−15%, 0%) of lower testosterone and 24% (8%, 42%) of higher progesterone concentrations. Substituting 30 min of moderate physical activity for sedentary behavior was associated with 15% (0%, 31%) of higher cortisol, whereas substituting the same amount of light physical activity for sedentary behavior was associated with 22% (−39%, 0%) of lower progesterone. Substituting 30 min of vigorous physical activity for sedentary behavior per day was associated with almost six times higher levels (5.83, 95% confidence interval = 1.79–9.86) of HSD11B2 methylation in boys.
Conclusions Accelerometer-measured daily physical activity was associated with reproductive hormones and HSD11B2 DNA methylation, differed by sex and activity intensity levels.
Exertional Rhabdomyolysis: A Retrospective Population-based Study
01-03-2020 – LUETMER, MARIANNE T.; BOETTCHER, BRENNAN J.; FRANCO, JOHN M.; REISNER, JACOB H.; CHEVILLE, ANDREA L.; FINNOFF, JONATHAN T.
Purpose This study aimed to evaluate the incidence and characteristics of exertional rhabdomyolysis (ER) in a population-based cohort.
Methods A retrospective cohort study was performed in Olmsted County, Minnesota, from 2003 to 2015. Incident ER cases were ascertained through the Rochester Epidemiology Project medical record linkage system through electronic searches of the International Classification of Diseases, Ninth Revision, codes and clinical note text. Population incidence rate was calculated using the corresponding Rochester Epidemiology Project census populations specific to calendar year and sex. Descriptive statistics were used.
Results Of the 430 patients, 431 cases met the inclusion criteria for rhabdomyolysis; 4.9% of cases (n = 20; males n = 18; Caucasian n = 17) were ER, with one recurrence. There were no deaths secondary to ER. The age- and sex-adjusted incidence rate of ER was 1.06 ± 0.24 (95% confidence interval = 0.59–1.52) per 100,000 person-years. Endurance activity (n = 7), manual labor (n = 5), and weight lifting (n = 4) were common causes. Complications included kidney injury (n = 5), mild electrolyte abnormalities (n = 10), elevated transaminases (n = 12), and minor electrocardiographic abnormalities (n = 4). A majority of patients were hospitalized (n = 16) for a median of 2 d, had mild abnormalities in renal and liver function and electrolytes, and were discharged without sequelae.
Conclusion ER in the civilian population occurs at a much lower incidence than the military population. The most common causes were endurance exercise, manual labor, and weight lifting. The majority of cases were treated conservatively with intravenous fluid resuscitation during a brief hospital stay, and all were discharged without sequela. Only one case of recurrence occurred in this cohort, indicating the recurrence rate was low.
Longitudinal Associations between Physical Fitness and Academic Achievement in Youth
01-03-2020 – MCLOUGHLIN, GABRIELLA M.; BAI, YANG; WELK, GREGORY J.
Introduction Data from clinical trials have justified the promotion of fitness as a means to enhance facets of cognitive control and academic achievement in youth. However, such associations, when tested under real-world conditions, are equivocal. The purpose of this study, therefore, was to evaluate longitudinal associations between aerobic capacity (AC), weight status, and academic achievement within a large urban county.
Methods Longitudinal data were obtained from a sample of third, fifth, and seventh grade students in schools within an urban county in Georgia. Data on body mass index (BMI) were available from 11,639 students; AC data from 5735 students. Data on both indicators were obtained through the established Fitness
Gram assessment battery with 2-yr changes calculated using standardized Z scores. Academic achievement data were available from three subjects (math, science, and reading) for third, fifth, and seventh grade students, and 2-yr changes were computed using changes in Z scores for each test. Data were analyzed using generalized logistic models to test associations between change in BMI and AC in relation to changes in academic achievement.
Results Positive associations were observed between improvements in weight status and academic achievement for the fifth grade boys and girls (reading odds ratio OR, 1.47; 95% confidence interval CI, 1.25–1.72; science OR, 1.22; 95% CI, 1.04–1.42). Maintaining weight status was associated with improved scores in the third grade (math OR, 1.16; 95% CI, 1.012–1.327; reading OR, 1.47; 95% CI, 1.25–1.72) and fifth grade cohorts (math OR, 1.20; 95% CI, 1.00.1.43). For AC, no significant associations were found for any age cohort.
Conclusions Modest associations between improvements in weight status, AC, and academic achievement are noteworthy, despite the lack of statistical significance for AC. The results provide a robust evaluation of associations between fitness and academic achievement.
Physiological Profile of a 59-Year-Old Male World Record Holder Marathoner
01-03-2020 – LEPERS, ROMUALD; BONTEMPS, BASTIEN; LOUIS, JULIEN
Purpose This study assessed the cardiorespiratory capacity and running economy (RE) of a 59-yr-old ex-Olympian athlete who ran a marathon in 2:30:15 in 2019. The athlete retired from running at 32 yr old (best marathon performance: 2:13:59) for a 16-yr period after his participation at the Olympics.
Methods Heart rate (HR), oxygen uptake (V˙O2), ventilation (VE), blood lactate concentration (La), step frequency, and RE were measured during a treadmill-running test.
Results His HRmax, VEmax, Lamax, and V˙O2max were 165 bpm, 115 L·min−1, 5.7 mmol·L−1, and 65.4 m
L·kg−1·min−1, respectively. At his marathon pace, his RE was 210 m
L·kg−1·min−1 with a step frequency of 199 ± 0.55 s·min−1, and his V˙O2 corresponded to 91% of his V˙O2max.
Conclusion This study shows that despite a 16-yr break in training, this 59-yr-old former Olympian marathoner has managed to limit the age-related decline in performance to ~5% per decade. More generally, these data suggest that high-level endurance masters athletes can limit the age-related decline in endurance performance at least until the age of 60 yr and can preserve their ability to sustain high-intensity effort (>90% of V˙O2max) for long-duration (2–3 h) exercises.
Lifelong Physical Activity Determines Vascular Function in Late Postmenopausal Women
01-03-2020 – GLIEMANN, LASSE; RYTTER, NICOLAI; TAMARIZ-ELLEMANN, ANDREA; EGELUND, JON; BRANDT, NINA; CARTER, HOWARD H.; HELLSTEN, YLVA
Introduction The study evaluated the role of lifelong physical activity for leg vascular function in postmenopausal women (61 ± 1 yr).
Method The study design was cross-sectional with three different groups based on self-reported physical activity level with regard to intensity and volume over the past decade: inactive (n = 14), moderately active (n = 12), and very active (n = 15). Endothelial-dependent and smooth muscle-dependent leg vascular function were assessed by ultrasound Doppler measurements of the femoral artery during infusion of acetylcholine (Ach), the nitric oxide (NO) donor sodium nitroprusside and the prostacyclin analog epoprostenol. Thigh muscle biopsies, arterial and venous plasma samples were obtained for assessment of vasodilator systems.
Results The very active group was found to have 76% greater responsiveness to Ach compared with the sedentary group accompanied by 200% higher prostacyclin synthesis during Ach infusion. Smooth muscle cell responsiveness to sodium nitroprusside and epoprostenol was not different between groups. The protein amount of endothelial NO synthase and endogenous antioxidant enzymes in muscle tissue was higher in the very active than the inactive group. The moderately active group had a similar endothelial and smooth muscle cell responsiveness as the inactive group. A secondary comparison with a smaller group (n = 5) of habitually active young (24 ± 2 yr) women indicated that smooth muscle cell responsiveness and endothelial responsiveness are affected by age per se.
Conclusions This study shows that leg vascular function and the potential to form prostacyclin and NO in late postmenopausal women, is influenced by the extent of lifelong physical activity.
Daily Changes of Resting Metabolic Rate in Elite Rugby Union Players
01-03-2020 – HUDSON, JAMES F.; COLE, MATTHEW; MORTON, JAMES P.; STEWART, CLAIRE E.; CLOSE, GRAEME L.
Introduction Preparation for competitive contact sport has been extensively researched. There are, however, limited data to guide players as to how the demands of their sport affect the energy requirements of recovery. We aimed to provide novel data on changes in resting metabolic rate (RMR) in contact sport athletes and relate these to the physical demands of training and competition.
Methods Twenty-two elite professional Premiership Rugby Union players were recruited to the study. Indirect calorimetry (Vyntus CPX canopy; Care
Fusion) was used to measure RMR each morning of the competitive game week, in a fasted, rested state. External loads for training and game play were monitored and recorded using global positioning systems (Catapult Innovations, Australia), whereas internal loads were tracked using rate of perceived exertion scales. Collisions were reviewed and recorded by expert video analysts for contacts in general play (breakdown and tackle area) or the set piece (scrum or maul).
Results There were significant (P = 0.005) mean increases in RMR of approximately 231 kcal the morning after (game day GD + 1) and 3 d after the game (GD + 3), compared with the day before the game (GD − 1). The players were exposed to internal and external loads during the training week comparable to that of a match day; however, despite the equivocal loads between training and game play, there were no significant increases in RMR after training.
Conclusion The collisions experienced in rugby match play are likely to be responsible for the significant increases in RMR at GD + 1 and GD + 3. Consequently, the measurement of RMR via indirect calorimetry may provide a novel noninvasive measure of the effects of collisions. This study provides a novel insight to the energy requirements of recovering from contact sport.
The Basics of Training for Muscle Size and Strength: A Brief Review on the Theory
01-03-2020 – BUCKNER, SAMUEL L.; JESSEE, MATTHEW B.; MOUSER, J. GRANT; DANKEL, SCOTT J.; MATTOCKS, KEVIN T.; BELL, ZACHARY W.; ABE, TAKASHI; LOENNEKE, JEREMY P.
The periodization of resistance exercise is often touted as the most effective strategy for optimizing muscle size and strength adaptations. This narrative persists despite a lack of experimental evidence to demonstrate its superiority. In addition, the general adaptation syndrome, which provides the theoretical framework underlying periodization, does not appear to provide a strong physiological rationale that periodization is necessary. Hans Selye conducted a series of rodent studies which used toxic stressors to facilitate the development of the general adaptation syndrome. To our knowledge, normal exercise in humans has never been shown to produce a general adaptation syndrome. We question whether there is any physiological rationale that a periodized training approach would facilitate greater adaptations compared with nonperiodized approaches employing progressive overload. The purpose of this article is to briefly review currently debated topics within strength and conditioning and provide some practical insight regarding the implications these reevaluations of the literature may have for resistance exercise and periodization. In addition, we provide some suggestions for the continued advancement within the field of strength and conditioning.
Effects of Exercise on Plantar Pressure during Walking in Children with Overweight/Obesity
01-03-2020 – MOLINA-GARCIA, PABLO; MIRANDA-APARICIO, DAMIAN; MOLINA-MOLINA, ALEJANDRO; PLAZA-FLORIDO, ABEL; MIGUELES, JAIRO H.; MORA-GONZALEZ, JOSE; CADENAS-SANCHEZ, CRISTINA; ESTEBAN-CORNEJO, IRENE; RODRIGUEZ-AYLLON, MARIA; SOLIS-URRA, PATRICIO; VANRENTERGHEM, JOS; ORTEGA, FRANCISCO B.
Purpose To investigate the effect of a 13-wk exercise program, based on “movement quality” and “multigames” work, on plantar pressure during walking in children with overweight/obesity (OW/OB).
Method Seventy children (10.8 ± 1.2 yr, 58.5% girls) with OW/OB, as defined by the World Obesity Federation, were assigned to either a 13-wk exercise program (intervention group EG; n = 39), or to a usual lifestyle control group (CG) (n = 31). Children underwent assessments of basic anthropometry (weight and height) and plantar pressure during walking before and after the intervention period, recording plantar surface area (cm2), maximum force (N), and force–time integrals (N·s−1).
Results After the 13-wk intervention period, the EG participants showed no significant change in total plantar surface area, while the CG participants experienced an increase in this variable (small effect size, −2.5 SD; P = 0.015). Compared with the GC participants, the EG participants showed a greater increase in the maximum force supported beneath the forefoot during walking at the end of the intervention period (small effect size, 0.33 SD; P = 0.012), specifically under the lateral and medial forefoot (both P 0.05).
Conclusions These results suggest the exercise program led to positive structural and functional changes in plantar pressure during walking. The increase in maximum force supported by the forefoot in the EG children might indicate a change toward a more normal foot rollover pattern and a more adult gait.
Ankle Coordination in Chronic Ankle Instability, Coper, and Control Groups in Running
01-03-2020 – KWON, YONG UNG; HARRISON, KATHRYN; KWEON, SANG JIN; WILLIAMS, D. S. BLAISE III
Purpose Coordination and coordination variability have been used as a measure of the function and flexibility of the sensorimotor system during running. Chronic ankle instability (CAI) is associated with altered sensorimotor system function compared with individuals without CAI. Copers may have adopted protective sensorimotor adaptations to prevent repeated ankle sprains; however, their coordination strategies between the foot and shank have not been investigated. We compared joint coupling angles and coordination variability using vector coding between individuals with CAI, copers, and controls.
Methods Seventeen individuals with CAI, 17 copers, and 17 controls ran on the treadmill at a fixed speed of 2.68 m·s−1. A 10-s trial of continuous data was collected for kinematic analysis. The first five complete strides were used for vector coding. Means of the vector coding angles and variability of frontal plane ankle motion/transverse plane tibia motion and sagittal plane ankle motion/transverse plane tibia motion (SAK/TT) were calculated. A curve analysis with 90% confidence intervals was performed to detect differences between groups.
Results Controls demonstrated greater angles of SAK/TT than individuals with CAI and greater angles of FAK/TT than copers during the second half of stance. In general, the control group demonstrated greater variability than individuals with CAI and copers, and copers demonstrated greater variability than individuals with CAI.
Conclusions Chronic ankle instability and copers demonstrated different coordination strategies than controls during loading and propulsion, adding evidence to support a sensorimotor deficit or compensation. Further, limited variability in people with history of CAI during impact and midstance may contribute to higher risk of reinjury, and be an important area for further research.
Can Static Stretching Reduce Stiffness of the Triceps Surae in Older Men?
01-03-2020 – HIRATA, KOSUKE; YAMADERA, RYOSUKE; AKAGI, RYOTA
Purpose The purpose of this study was to investigate reductions of muscle stiffness induced by static stretching in older and younger men.
Methods Twenty older (62–83 yr) and 20 younger (21–24 yr) men were recruited. Ankle dorsiflexion static stretching was consisted of 90 s × 5 repetitions. Before and after the stretching, the dorsiflexion range of motion (Ro
M), passive plantar flexion torque, and shear modulus (an index of stiffness) of the medial (MG) and lateral gastrocnemius and the soleus were measured.
M, passive torque, and shear modulus of the triceps surae measured at the maximal dorsiflexion angle before stretching were significantly lower for the older group than the younger group. This suggests a weak stretching intensity for older compared with younger people. The stretching significantly improved Ro
M for both groups. For the older group, a significant reduction in passive torque was only observed at a 15° dorsiflexion angle, and the shear modulus was significantly decreased only for the distal region of MG. For the younger group, passive torque was significantly reduced for the entire Ro
M, and a significant decrease in shear modulus was found for the central and distal regions of MG and lateral gastrocnemius. A significant correlation between the muscle shear modulus measured at the maximal dorsiflexion angle before stretching and a stretching-induced decrease in muscle shear modulus was observed for older and younger participants. This indicates that the higher stretching intensity can reduce more muscle stiffness.
Conclusion Static stretching can reduce muscle stiffness regardless of age, although the stretching effect on muscle stiffness was limited for older people. This might be due to a lower stretching intensity for older than younger people.
Is the Normal Shoulder Rotation Strength Ratio Altered in Elite Swimmers?
01-03-2020 – BOETTCHER, CRAIG; HALAKI, MARK; HOLT, KYLIE; GINN, KAREN A.
Introduction It is commonly believed that the shoulder external rotation (ER) to internal rotation (IR) strength ratio is decreased in swimmers due to predominant IR loading during the pull-through (propulsive) phase which predisposes to shoulder pain. However, the evidence supporting this hypothesis is inconclusive. Therefore, the aim of this study was to examine shoulder rotation strength parameters in elite swimmers and investigate potential associations with shoulder pain.
Methods Sixty-eight (40 men; age, 19.9 ± 3.2 yr) elite swimmers provided demographic and shoulder pain history data before measurement of shoulder rotation strength. Mixed model analyses were used to examine differences in shoulder IR and ER strength normalized to body weight (BW) and the shoulder rotation strength ratio. A multinomial logistic regression model was utilized to examine associations between shoulder rotation strength parameters and shoulder pain.
Results Mean shoulder IR strength (BW) was approximately 0.29 for male swimmers and 0.26 for female swimmers. Mean shoulder ER strength (BW) was approximately 0.19 for male swimmers and 0.18 for female swimmer. The shoulder ER/IR strength ratio was approximately 0.70 bilaterally for all swimmers. There were no significant differences between dominant and nondominant shoulders in IR or ER strength normalized to BW (P ≥ 0.547). There were no associations between any shoulder strength parameters and shoulder pain (r2 = 0.032, P = 0.107).
Conclusions Despite the high IR loading, optimal swimming technique does not alter the normal ER/IR strength ratio at the shoulder. Elite swimmers who report current or a history of shoulder pain demonstrate normal shoulder rotation strength ratios. The finding of symmetrical shoulder rotation strength points to side-to-side strength comparisons as a valuable clinical tool in managing swimmers with unilateral shoulder pain.
Compression Garments Reduce Muscle Movement and Activation during Submaximal Running
01-03-2020 – BROATCH, JAMES R.; BROPHY-WILLIAMS, NED; PHILLIPS, ELISSA J.; O’BRYAN, STEVEN J.; HALSON, SHONA L.; BARNES, SHANNON; BISHOP, DAVID J.
Purpose The purpose of this study was to investigate the effectiveness of sports compression tights in reducing muscle movement and activation during running.
Methods A total of 27 recreationally active males were recruited across two separate studies. For study 1, 13 participants (mean ± SD = 84.1 ± 9.4 kg, 22 ± 3 yr) completed two 4-min treadmill running bouts (2 min at 12 and 15 km·h−1) under two conditions: a no-compression control (CON1) and compression (COMP). For study 2, 14 participants (77.8 ± 8.4 kg, 27 ± 5 yr) completed four 9-min treadmill running bouts (3 min at 8, 10, and 12 km·h−1) under four conditions: a no-compression control (CON2) and three different commercially available compression tights (2XU, Nike, and Under Armor). Using Vicon 3D motion capture technology, lower limb muscle displacement was investigated in both study 1 (thigh and calf) and study 2 (vastus lateralis + medialis VAS; lateral + medial gastrocnemius GAS). In addition, study 2 investigated the effects of compression on soft tissue vibrations (root-mean-square of resultant acceleration, RMS Ar), muscle activation (i
EMG), and running economy (oxygen consumption, V˙O2) during treadmill running.
Results Wearing compression during treadmill running reduced thigh and calf muscle displacement as compared with no compression (both studies), which was evident across all running speeds. Compression also reduced RMS Ar and i
EMG during treadmill running, but it had no effect on running economy (study 2).
Conclusion Lower limb compression garments are effective in reducing muscle displacement, soft tissue vibrations, and muscle activation associated with the impact forces experienced during running.
Increasing Students’ Activity in Physical Education: Results of the Self-determined Exercise and Learning For FITness Trial
01-03-2020 – HA, AMY S.; LONSDALE, CHRIS; LUBANS, DAVID R.; NG, JOHAN Y. Y.
Purpose To examine the effects of the Self-determined Exercise and Learning For FITness (SELF-FIT) intervention on students’ moderate-to-vigorous physical activity (MVPA) and motivation in physical education (PE).
Methods In a clustered randomized controlled trial, 667 students (mean age, 14.4 yr; SD, 0.78) from 26 schools (i.e., clusters) were randomized into either an experimental group or a waitlist control group. Students in the experimental group received the SELF-FIT intervention, a school-based intervention designed to infuse fitness and game-like elements into PE using self-determination theory principles, whereas those in the control continued their classes using usual practices. Intervention content was provided by teachers who received training from the research team. The primary outcome was percentage of time spent in MVPA during PE. Secondary outcomes included basic psychological need satisfaction, motivation toward PE, leisure-time MVPA, and mental well-being. Data were analyzed using multilevel regression analyses and prespecified interactions were tested (i.e., group–time–sex).
Results Positive intervention effects were found on MVPA during PE (B, 4.00; 95% confidence interval, 2.96–5.04; d = 0.36). Regarding the participants’ competence and autonomy need satisfaction, and autonomous motivation, the intervention effects were stronger in girls, compared with boys.
Conclusions Fitness infusion and game-like elements, used according to self-determination theory principles, can enhance students’ physical activity and motivation toward PE. This low-cost intervention has the potential to be scaled up and disseminated in secondary schools.
Exercise Core Temperature Response with a Simulated Burn Injury: Effect of Body Size
01-03-2020 – CRAMER, MATTHEW N.; MORALEZ, GILBERT; HUANG, MU; KOUDA, KEN; POH, PAULA Y. S.; CRANDALL, CRAIG G.
Although the severity of a burn injury is often associated with the percentage of total body surface area burned (%TBSA), the thermoregulatory consequences of a given %TBSA injury do not account for the interactive effects of body morphology and metabolic heat production (Hprod).
Purpose Using a simulated burn injury model to mimic the detrimental effect of a 40% TBSA injury on whole-body evaporative heat dissipation, core temperature response to exercise in physiologically uncompensable conditions between morphologically disparate groups were examined at (i) an absolute Hprod (W), and (ii) a mass-specific Hprod (W·kg−1).
Methods Healthy, young, nonburned individuals of small (SM, n = 11) or large (LG, n = 11) body size cycled for 60 min at 500 W or 5.3 W·kg−1 of Hprod in 39°C and 20% relative humidity conditions. A 40% burn injury was simulated by affixing a highly absorbent, vapor-impermeable material across the torso (20% TBSA), arms (10% TBSA), and legs (10% TBSA) to impede evaporative heat loss in those regions.
Results Although the elevation in core temperature was greater in SM compared with LG at an Hprod of 500 W (SM, 1.69°C ± 0.26°C; LG, 1.05°C ± 0.26°C; P < 0.01), elevations in core temperature were not different at an Hprod of 5.3 W·kg−1 between groups (SM, 0.99°C ± 0.32°C; LG, 1.05°C ± 0.26°C; P = 0.66).
Conclusions These data suggest that among individuals with a 40% TBSA burn injury, a smaller body size leads to exacerbated elevations in core temperature during physical activities eliciting the same absolute Hprod (non–weight-bearing tasks) but not activities eliciting the same mass-specific Hprod (weight-bearing tasks).
Exercise Thermoregulation with a Simulated Burn Injury: Impact of Air Temperature
01-03-2020 – CRAMER, MATTHEW N.; MORALEZ, GILBERT; HUANG, MU; KOUDA, KEN; POH, PAULA Y. S.; CRANDALL, CRAIG G.
S. Army’s Standards of Medical Fitness (AR 40-501) states: “Prior burn injury (to include donor sites) involving a total body surface area of 40% or more does not meet the standard.” However, the standard does not account for the interactive effect of burn injury size and air temperature on exercise thermoregulation.
Purpose To evaluate whether the detrimental effect of a simulated burn injury on exercise thermoregulation is dependent on air temperature.
Methods On eight occasions, nine males cycled for 60 min at a fixed metabolic heat production (6 W·kg−1) in air temperatures of 40°C or 25°C with simulated burn injuries of 0% (Control), 20%, 40%, or 60% of total body surface area (TBSA). Burn injuries were simulated by covering the skin with an absorbent, vapor-impermeable material to impede evaporation from the covered areas. Core temperature was measured in the gastrointestinal tract via telemetric pill.
Results In 40°C conditions, greater elevations in core temperature were observed with 40% and 60% TBSA simulated burn injuries versus Control (P < 0.01). However, at 25°C, core temperature responses were not different versus Control with 20%, 40%, and 60% TBSA simulated injuries (P = 0.97). The elevation in core temperature at the end of exercise was greater in the 40°C environment with 20%, 40%, and 60% TBSA simulated burn injuries (P ≤ 0.04).
Conclusions Simulated burn injuries ≥20% TBSA exacerbate core temperature responses in hot, but not temperate, air temperatures. These findings suggest that the U.
S. Army’s standard for inclusion of burned soldiers is appropriate for hot conditions, but could lead to the needless discharge of soldiers who could safely perform their duties in cooler training/operational settings.
Impact of Exercise–Nutritional State Interactions in Patients with Type 2 Diabetes
01-03-2020 – VERBOVEN, KENNETH; WENS, INEZ; VANDENABEELE, FRANK; STEVENS, AN; CELIE, BERT; LAPAUW, BRUNO; DENDALE, PAUL; VAN LOON, LUC J. C.; CALDERS, PATRICK; HANSEN, DOMINIQUE
Introduction This study examines the role of nutritional status during exercise training in patients with type 2 diabetes mellitus by investigating the effect of endurance-type exercise training in the fasted versus the fed state on clinical outcome measures, glycemic control, and skeletal muscle characteristics in male type 2 diabetes patients.
Methods Twenty-five male patients (glycated hemoglobin (Hb
A1c), 57 ± 3 mmol·mol−1 (7.4% ± 0.3%)) participated in a randomized 12-wk supervised endurance-type exercise intervention, with exercise being performed in an overnight-fasted state (n = 13) or after consuming breakfast (n = 12). Patients were evaluated for glycemic control, blood lipid profiles, body composition and physical fitness, and skeletal muscle gene expression.
Results Exercise training was well tolerated without any incident of hypoglycemia. Exercise training significantly decreased whole-body fat mass (−1.6 kg) and increased high-density lipoprotein concentrations (+2 mg·d
L−1), physical fitness (+1.7 m
L·min−1·kg−1), and fat oxidation during exercise in both groups (PTIME 0.05). Hb
A1c concentrations significantly decreased after exercise training (PTIME < 0.001), with a significant greater reduction after consuming breakfast (−0.30% ± 0.06%) compared with fasted state (−0.08% ± 0.06%; mean difference, 0.21%; PTIME × GROUP = 0.016). No interaction effects were observed for skeletal muscle genes related to lipid metabolism or oxidative capacity.
Conclusions Endurance-type exercise training in the fasted or fed state do not differ in their efficacy to reduce fat mass, increase fat oxidation capacity, and increase cardiorespiratory fitness and high-density lipoprotein concentrations or their risk of hypoglycemia in male patients with type 2 diabetes. Hb
A1c seems to be improved more with exercise performed in the postprandial compared with the postabsorptive state.
Interval Exercise Lowers Circulating CD105 Extracellular Vesicles in Prediabetes
01-03-2020 – EICHNER, NATALIE Z. M.; GILBERTSON, NICOLE M.; HEISTON, EMILY M.; MUSANTE, LUCA; LA SALVIA, SABRINA; WELTMAN, ARTHUR; ERDBRUGGER, UTA; MALIN, STEVEN K.
Background Extracellular vesicles (EV) are purported to mediate type 2 diabetes and CVD risk and development. Physical activity and a balanced diet reduce disease risk, but no study has tested the hypothesis that short-term interval (INT) training would reduce EV compared with continuous (CONT) exercise in adults with prediabetes.
Methods Eighteen obese adults (age, 63.8 ± 1.5 yr; body mass index, 31.0 ± 1.3 kg·m−2) were screened for prediabetes using American Diabetes Association criteria (75 g oral glucose tolerance test). Subjects were randomized to INT (n = 10, alternating 3-min intervals at 90% and 50% HRpeak, respectively) or CONT (n = 8, 70% HRpeak) training for 12 supervised sessions over 13 d for 60 min·d−1. Cardiorespiratory fitness (V˙ O2peak), weight (kg), as well as ad libitum dietary intake were assessed and arterial stiffness (augmentation index via applanation tonometry) was calculated using total AUC during a 75-g oral glucose tolerance test performed 24 h after the last exercise bout. Total EV, platelet EV (CD31+/CD41+), endothelial EV (CD105; CD31+/ CD41−), platelet endothelial cell adhesion molecule (PECAM) (CD31+), and leukocyte EV (CD45+; CD45+/CD41−) were analyzed via imaging flow cytometry preintervention/postintervention.
Results The INT exercise increased V˙O2peak (P = 0.04) compared with CONT training. Although training had no effect on platelet or leukocyte EV, INT decreased Annexin V− endothelial EV CD105 compared with CONT (P = 0.04). However, after accounting for dietary sugar intake, the intensity effect was lost (P = 0.18). Increased ad libitum dietary sugar intake after training was linked to elevated AV+ CD105 (r = 0.49, P = 0.06) and AV− CD45+ (r = 0.59, P = 0.01). Nonetheless, increased V˙O2peak correlated with decreased AV+ CD105 (r = −0.60, P = 0.01).
Conclusions Interval exercise training decreases endothelial-derived EV in adults with prediabetes. Although increased sugar consumption may alter EV after a short-term exercise intervention, fitness modifies EV count.
Moderate-Intensity Continuous Training or High-Intensity Interval Training with or without Resistance Training for Altering Body Composition in Postmenopausal Women
01-03-2020 – DUPUIT, MARINE; RANCE, MÉLANIE; MOREL, CLAIRE; BOUILLON, PATRICE; PEREIRA, BRUNO; BONNET, ALBAN; MAILLARD, FLORIE; DUCLOS, MARTINE; BOISSEAU, NATHALIE
Purpose This study aimed to compare body composition changes induced by moderate-intensity continuous training (MICT), high-intensity interval training (HIIT), or HIIT + resistance training (RT) programs (3 d·wk−1, 12 wk) in overweight/obese postmenopausal women, and to determine whether fat mass reduction is related to greater fat oxidation (Fat
Methods Participants (n = 27) were randomized in three groups: MICT (40 min at 55%–60% of peak power output), HIIT (60 × 8 s at 80%–90% of peak HR, 12 s active recovery), and HIIT + RT (HIIT + 8 whole-body exercises: 1 set of 8–12 repetitions). Dual-energy x-ray absorptiometry was used to measure whole-body and abdominal/visceral fat mass (FM) and fat-free mass. Fat
Ox was determined at rest, during a moderate-intensity exercise (40 min at 50% of peak power output), and for 20 min postexercise, before and after training.
Results Overall, energy intake and physical activity levels did not vary from the beginning to the end of the intervention. Body weight and total FM decreased in all groups over time, but significant abdominal/visceral FM losses were observed only in HIIT and HIIT + RT groups. When expressed in percentage, total FM, fat-free mass, and muscle mass were significantly modified only by HIIT + RT training. Fat
Ox did not change at rest but increased similarly in the three groups during and after exercise. Therefore, the HIIT-induced greater FM loss was not related to higher Fat
Ox during or after exercise.
Conclusions MICT or HIIT ± RT could be proposed to nondieting postmenopausal women who are overweight/obese to decrease weight and whole-body FM. The HIIT programs were more effective than MICT in reducing abdominal/visceral FM. RT addition did not potentiate this effect but increased the percentage of muscle mass.
Effect of Cuff Pressure on Blood Flow during Blood Flow–restricted Rest and Exercise
01-03-2020 – CROSSLEY, KENT W.; PORTER, DORAN A.; ELLSWORTH, JOSHUA; CALDWELL, TABITHA; FELAND, J. BRENT; MITCHELL, ULRIKE; JOHNSON, A. WAYNE; EGGET, DENNIS; GIFFORD, JAYSON R.
Purpose This study investigated the relationship between blood flow restriction (BFR) cuff pressure and blood flow at rest and during exercise, with the aim of determining if lower cuff pressures will provide an ischemic stimulus comparable to higher pressures.
Methods The relationship between blood flow and cuff pressure at rest was determined by measuring blood flow (Doppler Ultrasound) through the superficial femoral artery (SFA) in 23 adults across a range of pressures (0%–100% Arterial Occlusion Pressure at rest r
AOP). The interplay between cuff pressure, blood flow and exercise was assessed by determining AOP at rest and during plantar flexion exercise (e
AOP) and subsequently measuring the blood flow response to plantar flexion exercise with BFR cuff pressure set to either 40% r
AOP or 40% e
Results At rest, a nonlinear relationship between cuff pressure and blood flow through the SFA exhibited a plateau at moderate pressures, with nonsignificant differences in blood flow (~9%, P = 1.0) appearing between pressures ranging from 40% to 80% r
AOP. While e
AOP was greater than r
AOP (229 ± 1.5 mm Hg vs 202 ± 1.5 mm Hg, P < 0.01), blood flow during plantar flexion exercise did not significantly differ (P = 0.49) when applying 40% r
AOP or 40% e
Conclusions Blood flow through the SFA exhibits a nonlinear relationship with cuff pressure, such that cuff pressures in the range of 40% to 80% r
AOP reduce blood flow to approximately the same degree. The BFR interventions opting for lower (e.g., 40% AOP), more comfortable pressures will likely provide an ischemic stimulus comparable to that of higher (80% AOP), less-comfortable pressures.
Effects of Exergaming on Cognition and Gait in Older Adults at Risk for Falling
01-03-2020 – OGAWA, ELISA F.; HUANG, HAIKUN; YU, LAP-FAI; GONA, PHILIMON N.; FLEMING, RICHARD K.; LEVEILLE, SUZANNE G.; YOU, TONGJIAN
Purpose To test whether an 8-wk exergaming (EG) program would improve cognition and gait characteristics compared with a traditional physical exercise (TPE) program in older adults at risk for falling.
Methods A pilot quasi-experimental study was conducted in adults age ≥65 yr at risk for falls, living in senior communities. Participants enrolled (n = 35) in either exercise program offered twice weekly for 8 wk. Cognition and single-task and dual-task gait characteristics were measured before and after the 8-wk exercise intervention. For each outcome, a repeated-measures ANCOVA adjusted for age, gender, and exercise intensity (ratings of perceived exertion, RPE) was used to examine the group–time interaction.
Results Twenty-nine participants (age, 77 ± 7 yr) completed either the EG program (n = 15) or the TPE program (n = 14). Statistically significant group–time interactions were observed in Trail Making Test Part A (P < 0.05) and single-task gait speed, stride length, swing time percentage, and double support percentage (all P < 0.05), and marginal group differences were observed in Mini-Mental State Examination (P = 0.07), all favoring the EG program. There were no statistically significant group differences in dual-task gait measurements except for swing time percentage and double support percentage, favoring the EG program.
Conclusions An 8-wk EG program for older adults at risk for falls contributed to modest improvements in a number of cognitive measures and single-task but limited improvements in dual-task gait measures, compared with TPE. These findings support the need for larger trials to determine cognitive and mobility benefits related to EG.
The Anthropometry of Economical Running
01-03-2020 – BLACK, MATTHEW I.; ALLEN, SAM J.; FORRESTER, STEPH E.; FOLLAND, JONATHAN P.
The influence of anthropometry and body composition on running economy is unclear, with previous investigations involving small relatively homogeneous groups of runners and limited anthropometric/composition measurements.
Purpose To comprehensively investigate the relationships of anthropometry and body composition with running economy within a large heterogeneous sample of runners.
Methods Eighty-five runners (males M, n = 45; females F, n = 40), of diverse competitive standard, performed a discontinuous protocol of incremental treadmill running (4-min stages, 1 km·h−1 increments) to establish locomotory energy cost (LEc) of running at submaximal speeds (averaged across 10–12 km·h−1; the highest common speed < lactate turnpoint). Measurements of anthropometry, including segment lengths, perimeters, masses and moments of inertia, and body composition were obtained using tape-based measurements and dual-energy x-ray absorptiometry.
Results Absolute LEc (ABSLEc, kcal·km−1) was positively correlated with 21 (of 27) absolute anthropometric variables in both male and female cohorts. Multiple-regression analyses revealed that one variable (mean perimeter z score) explained 49.4% (M) and 68.9% (F) of the variance in ABSLEc. Relative LEc (RELLEc, kcal·kg−1·km−1) was also correlated with five (M) and seven (F) normalized anthropometric variables, and regression analyses explained 31.6% (M; percentage bone mass and normalized hip perimeter) and 33.3% (F, normalized forearm perimeter) of the variance in RELLEc.
Conclusions These findings provide novel and robust evidence that anthropometry and body composition variables, predominantly indicative of relative slenderness, explain a considerable proportion of the variance in running economy (i.e., more slender, lower energy cost). We, therefore, recommend that runners and coaches are attentive to relative slenderness in selecting and training athletes with the aim of enhancing running economy, and improving distance running performance.
Assessments for Sport and Athletics Performance
No abstract available
Baseball Sports Medicine
No abstract available