Medicine and Science in Sports and Exercise

Medicine and Science in Sports and Exercise

Translational Medicine: Exercise Physiology Applied to Metabolic Myopathies

01-11-2019 – GRASSI, BRUNO; PORCELLI, SIMONE; MARZORATI, MAURO

The relevance of translational medicine (bringing basic science methods “to the bed of patients”) is universally recognized. Too often, however, the tools to be applied translationally are thought to derive only from the “-omics” (genomics, proteomics, transcriptomics, metabolomics, etc.) world. The failures of this “reductionist” approach are widely recognized. In the review, we discuss studies demonstrating that scientifically sound mechanistic insights into diseases, relevant both in terms of basic science and clinically, and very well suited to be utilized within a translational medicine approach, can be obtained from the established field of exercise physiology. Methods originally aimed toward basic physiological mechanisms, and applied for the functional evaluation of athletes and sport performance, can have a valuable translational application in patients with metabolic myopathies; such as myophosphorylase deficiency (McArdle disease) or mitochondrial myopathies, diseases which share the common denominator of an impaired skeletal muscle oxidative metabolism. Several variables can yield pathophysiological insights, can identify and quantify the metabolic impairment and the effects on exercise tolerance (one of the main determinants of the patients’ clinical picture and quality of life), and can offer diagnostic clues: the impaired capacity of O2 extraction by skeletal muscle, evaluated by near-infrared spectroscopy; the “exaggerated” cardiovascular response to exercise; the slower speed of adjustment of oxidative metabolism during metabolic transitions; the “slow component” of pulmonary O2 uptake kinetics and the associated reduced efficiency and fatigue; the impaired intramuscular matching between O2 delivery and O2 utilization. The proposed methods are noninvasive, and therefore facilitate repeated or serial evaluations. They provide support for a simple message: physiology and physiological research remain the essential link between genes, molecules, and clinical care.

High-Intensity Interval Training Is Feasible in Women at High Risk for Breast Cancer

01-11-2019 – COLETTA, ADRIANA M.; BREWSTER, ABENAA M.; CHEN, MINXING; LI, YISHENG; BEVERS, THERESE B.; BASEN-ENGQUIST, KAREN; GILCHRIST, SUSAN C.

Journal Article

Purpose This trial aimed to demonstrate the feasibility of high-intensity interval training (HIIT) in postmenopausal, overweight/obese women at high risk of invasive breast cancer and to explore HIIT on changes in cardiorespiratory fitness (CRF), body weight, and body mass index (BMI) compared with moderate-intensity continuous training (MICT) and usual care (UC).
Methods Forty-four women were randomized to HIIT, MICT, or UC for a 12-wk, thrice weekly, supervised exercise intervention. HIIT included a 5-min warm-up at 50%–70% HRpeak, four cycles of 4 min at 90%–100% HRpeak, followed by 3 min at 50%–70% HRpeak. MICT consisted of 41 min at 60%–70% HRpeak. Feasibility was assessed by consent, adherence, compliance, and retention rates. CRF, body weight, and BMI were measured at baseline and end of study. Repeated-measures linear mixed models were used to assess within- and between-group differences.
Results Average age was 63.9 ± 8.8 yr. BMI was 30.9 ± 5.7 kg·m−2. Participants completed 90% and 89% of HIIT and MICT workouts, respectively, with 100% compliance to the exercise prescriptions. No serious adverse events were reported. Compared with MICT and UC, HIIT exhibited improvements in change in treadmill time (101 s greater than MICT, and 125 s greater than UC, respectively, P 0.05).
Conclusions HIIT is feasible, safe, and seems to promote greater improvements in CRF compared with MICT and UC in women at high risk for breast cancer.

The Effect of Growth Restriction on Voluntary Physical Activity Engagement in Mice

01-11-2019 – LESZCZYNSKI, ERIC C.; VISKER, JOSEPH R.; FERGUSON, DAVID P.

Journal Article

Introduction The purpose of this study was to determine the effect of growth restriction on the biological regulation of physical activity.
Methods Using a cross-fostering, protein-restricted nutritive model, mice were growth-restricted during either gestation (GUN; N = 3 litters) or postnatal life (PUN; N = 3 litters). At 21 d of age, all mice pups were weaned and fed a nonrestrictive healthy diet for the remainder of the study. At 45 d of age, mice were individually housed in cages with free moving running wheels to assess physical activity engagement. At day 70, mice were euthanized, and the nucleus accumbens was analyzed for dopamine receptor 1 expression. Skeletal muscle fiber type and cross-sectional area of the soleus, extensor digitorom longus, and diaphragm were analyzed by immunohistochemistry. The soleus from the other hindleg was evaluated for calsequestrin 1 and annexin A6 expression.
Results The PUN female mice (15,365 ± 8844 revolutions per day) had a reduction (P = 0.0221) in wheel revolutions per day as compared with the GUN (38,667 ± 8648 revolutions per day) and CON females (36,421.0 ± 6700 revolutions per day). The PUN female mice also expressed significantly higher dopamine receptor 1 compared (P = 0.0247) to the other groups. The PUN female soleus had a higher expression of calsequestrin 1, along with more type IIb fibers (P = 0.0398).
Conclusions Growth restriction during lactation reduced physical activity in female mice by reducing the central drive to be active and displayed a more fatigable skeletal muscle phenotype.

Aerobic Training and Green Tea Extract Protect against N-methyl-N-nitrosourea–induced Prostate Cancer

01-11-2019 – SAEDMOCHESHI, SABER; SAGHEBJOO, MARZIYEH; VAHABZADEH, ZAKARIA; SHEIKHOLESLAMI-VATANI, DARIUSH

Journal Article

Introduction Aerobic training and green tea extract can be used to reduce the risk of prostate cancer. The goal of this study was to evaluate the effects of 8-wk aerobic exercise training and administration of green tea extract on the level of nuclear factor kappa B (NF-k
B), cyclooxygenase-2 (COX-2) and p53 tumor suppressor protein (p53) in prostate of rats which were stimulated by N-methyl-N-nitrosourea to induce the prostate cancer.
Methods Sixty adult male Wistar rats were assigned into six groups including healthy control, cancer control (CCt), cancer training (CTr: 45 min·d−1 at low to moderate intensity, five times per week, 8 wk), cancer extract (CEx: 1.34 m
L of green tea extract, three times per week, 8 wk), cancer training+ cancer extract (CTr + CEx) and sham groups. Rats were sacrificed 48 h after the last intervention session, and the prostate tissue was isolated to measure the levels of NF-k
B, COX-2, and p53.
Results The NF-k
B level in CCt group was increased significantly compared to the healthy control (P = 0.02). In the CTr group, NF-k
B level was decreased significantly compared to the CCt and CEx groups (P = 0.001 and 0.05, respectively). In addition, the levels of P53 protein were reduced in CTr, CEx, and CTr + CEx groups compared to CCt group (P = 0.001, 0.02 and 0.004, respectively). No significant changes were found in the level of COX-2 between groups.
Conclusions These results suggest that a long-term exercise training combined with the intake of green tea extract may reduce levels of NF-k
B and p53 in rats with prostate cancer. Given the importance of recognizing complementary therapies in this regard, future studies are warranted.

Community-Level Sports Group Participation and the Risk of Cognitive Impairment

01-11-2019 – TSUJI, TAISHI; KANAMORI, SATORU; MIYAGUNI, YASUHIRO; HANAZATO, MASAMICHI; KONDO, KATSUNORI

Journal Article

Purpose Community-level group participation is a structural aspect of social capital that may have a contextual influence on individual health. We investigated the contextual effect of community-level prevalence of sports group participation on the risk of cognitive impairment among older individuals.
Methods We analyzed prospective cohort data from the Japan Gerontological Evaluation Study, a nationwide survey of 40,308 functionally independent older individuals from 346 communities. Cognitive impairment was assessed by the nationally standardized dementia scale proposed by the Ministry of Health, Labour and Welfare of Japan. Participation in a sports group 1 d per month or more frequently was defined as “participation.” We applied a two-level multilevel survival analysis to calculate hazard ratios (HR) and 95% confidence intervals (CI).
Results The cumulative incidence of cognitive impairment during the 6-yr follow-up period was 9.8%. The mean proportion of sports group participation was 25.2% (range, 0.0%–56.5%). Higher prevalence of community-level sports group participation was associated with a lower risk of cognitive impairment (HR, 0.92; 95% CI, 0.86–0.99, estimated by 10 percentage points of participation proportion) after adjusting for individual-level sports group participation, sex, age, disease, obesity, social isolation, alcohol, smoking, education, income, depression, daily walking time, population density, and sunlight hours. We found cross-level interaction between individual- and community-level sports group participation (HR, 0.87; 95% CI, 0.76–0.99).
Conclusions We found a contextual preventive effect of community-level sports group participation on developing cognitive impairment among older individuals. Furthermore, the benefit may favor sports group participants. Therefore, promoting sports groups in a community setting may be effective as a population-based strategy for the prevention of dementia.

Optimal Approach to Load Progressions during Strength Training in Older Adults

01-11-2019 – BUSKARD, ANDREW N. L.; JACOBS, KEVIN A.; ELTOUKHY, MOATAZ M.; STRAND, KERI L.; VILLANUEVA, LAWRENCE; DESAI, PARTH P.; SIGNORILE, JOSEPH F.

Journal Article

Progressive resistance training (RT) is one of the most effective interventions for reducing age-related deficits in muscle mass and functional capacity.
Purpose To compare four approaches to load progressions in RT for older adults to determine if an optimal method exists.
Methods Eighty-two healthy community-dwelling older adults (71.8 ± 6.2 yr) performed 11 wk of structured RT (2.5 d·wk−1) in treatment groups differing only by the method used to increase training loads. These included percent one repetition maximum (%1RM): standardized loads based on a percentage of the one repetition maximum (1RM); rating of perceived exertion (RPE): loads increased when perceived difficulty falls below 8/10 on the OMNI-Resistance Exercise Scale perceived exertion scale; repetition maximum (RM): loads increased when a target number of repetitions can be completed with a given load; repetitions in reserve (Ri
R): identical to RM except subjects must always maintain ≥1 “repetition in reserve,” thus avoiding the possibility of training to temporary muscular failure.
Results Multiple analyses of covariance indicated no significant between-group differences on any strength (chest press 1RM; leg press 1RM) or functional performance outcome (usual walking speed, maximum walking speed, 8-ft timed up-and-go, gallon jug transfer test, 30 s sit-to-stand). The RPE group found the exercise to be significantly more tolerable and enjoyable than subjects in the Ri
R, RM, and %1RM groups.
Conclusion Given the RM, RPE, %1RM, and Ri
R methods appear equally effective at improving muscular strength and functional performance in an older population, we conclude that the RPE method is optimal because it is likely to be perceived as the most tolerable and enjoyable, which are two important factors determining older adults’ continued participation in RT.

High-Intensity Single-Leg Cycling Improves Cardiovascular Disease Risk Factor Profile

01-11-2019 – GORDON, NICOLE; ABBISS, CHRIS R.; MAIORANA, ANDREW J.; JAMES, ANTHONY P.; CLARK, KARIN; MARSTON, KIERAN J.; PEIFFER, JEREMIAH J.

Journal Article

Introduction Regular exercise can reduce the risk of developing cardiovascular disease through risk factor modification, with high-intensity exercise and more recently small muscle mass training providing alternatives to moderate-intensity exercise.
Methods This study randomly assigned 53 healthy middle-age adults (age, 62 ± 6 yr) to complete 24 sessions (8 wk; 3 d·wk−1) of exercise training, using either high-intensity double-leg cycling (n = 17; HITDL), high-intensity single-leg cycling (n = 18; HITSL), or moderate-intensity double-leg cycling (n = 18; MCTDL). Biomarkers of cardiovascular risk (total cholesterol, triglycerides, HDL-c, LDL-c, apo-B48, and glucose), anthropometry measures (body mass, body mass index, waist circumference, and waist-to-hip ratio), resting blood pressure, and aerobic capacity were assessed pre- and postintervention.
Results Total work completed was greater (P < 0.01) in MCTDL (5938 ± 1462 k
J) compared with the HITDL (3462 ± 1063 k
J) and HITSL (4423 ± 1875 k
J). Pre- to posttraining differences were observed for waist-to-hip ratio (0.84 ± 0.09 vs 0.83 ± 0.09; P < 0.01), resting systolic blood pressure (129 ± 11 vs 124 ± 12 mm Hg; P < 0.01), total cholesterol (5.87 ± 1.17 vs 5.55 ± 0.98 mmol·L−1; P < 0.01), and LDL-c (3.70 ± 1.04 vs 3.44 ± 0.84 mmol·L−1; P < 0.01), with no differences between conditions. In addition, aerobic capacity increased after training (22.3 ± 6.4 vs 24.9 ± 7.6 m
L·kg−1·min−1; P < 0.01), with no differences between conditions.
Conclusion These findings suggest that all three modes of exercise can be prescribed to achieve cardiovascular risk reduction in an aging population.

Quantification of Cardiorespiratory Fitness in Children with Obesity

01-11-2019 – BHAMMAR, DHARINI M.; ADAMS-HUET, BEVERLEY; BABB, TONY G.

Purpose Without consideration for the effects of fat mass, there could be an underestimation of cardiorespiratory fitness in children with obesity leading to a clinical diagnosis of deconditioning and resulting in unrealistic training goals and limitation of physical activities. The purpose of this study was to identify methods of quantifying cardiorespiratory fitness that were less influenced by fat mass.
Methods Fifty-three children, 27 with obesity (10.9 ± 1.0 yr) and 26 without obesity (11.0 ± 1.0 yr), volunteered for this study. Maximal oxygen uptake, an indicator of cardiorespiratory fitness, was referenced to lean body mass, body mass, and predicted body mass at the 50th and 85th body mass index percentiles.
Results Children with obesity carried 18 kg more fat mass and 7 kg more lean body mass compared with children without obesity. Cardiorespiratory fitness based on lean body mass, body mass, and predicted body mass at the 85th percentile was lower in children with obesity compared with children without obesity (P 0.37).
Conclusion Quantifying cardiorespiratory fitness based on lean body mass or predicted body mass at the 50th percentile could be useful for estimating fitness levels in children with obesity.

Validity of Cardiorespiratory Fitness Measured with Fitbit Compared to V˙O2max

01-11-2019 – KLEPIN, KATHARINE; WING, DAVID; HIGGINS, MICHAEL; NICHOLS, JEANNE; GODINO, JOB G.

Journal Article

Purpose Cardiorespiratory fitness (CRF), broadly defined as the body’s ability to utilize oxygen, is a well-established prognostic marker of health, but it is not routinely measured. This may be due to the difficulty of acquiring high-quality CRF measures. The purpose of this study was to independently determine the validity of the Fitbit Charge 2’s measure of CRF (Fitbit CRF).
Methods Sixty-five healthy adults between the ages of 18 and 45 yr (55% female, 45% male) were recruited to undergo gold standard V˙O2max testing and wear a Fitbit Charge 2 continuously for 1 wk during which they were instructed to complete a qualifying outdoor run to derive the Fitbit CRF (units: m
L·kg−1·min−1). This measure was compared with V˙O2max measures (units: m
L·kg−1·min−1) epoched at 15 and 60 s.
Results Bland–Altman analyses revealed that Fitbit CRF had a positive bias of 1.59 m
L·kg−1·min−1 compared with laboratory data epoched at 15 s and 0.30 m
L·kg−1·min−1 compared with data epoched at 60 s (n = 60). F statistics (2.09; 0.08) and P values (0.133; 0.926) from Bradley–Blackwood tests for the concordance of Fitbit CRF with 15- and 60-s laboratory data, respectively, support the null hypothesis of equal means and variances, indicating there is concordance between the two measures. Mean absolute percentage error was less than 10% for each comparison.
Conclusions The Fitbit Charge 2 provides an acceptable level of validity when measuring CRF in young, healthy, and fit adults who are able to run. Further research is required to determine if it is a potentially useful tool in clinical practice and epidemiological research to quantify, categorize, and longitudinally track risk for adverse outcomes.

Estimating Tibial Stress throughout the Duration of a Treadmill Run

01-11-2019 – RICE, HANNAH; WEIR, GILLIAN; TRUDEAU, MATTHIEU B.; MEARDON, STACEY; DERRICK, TIMOTHY; HAMILL, JOSEPH

Introduction Stress fractures of the tibia are a problematic injury among runners of all levels. Quantifying tibial stress using a modeling approach provides an alternative to invasive assessments that may be used to detect changes in tibial stress during running. This study aimed to assess the repeatability of a tibial stress model and to use this model to quantify changes in tibial stress that occur throughout the course of a 40-min prolonged treadmill run.
Methods Synchronized force and kinematic data were collected during prolonged treadmill running from 14 recreational male rearfoot runners on two separate occasions. During each session, participants ran at their preferred speed for two consecutive 20-min runs, separated by a 2-min pause. The tibia was modeled as a hollow ellipse and bending moments and stresses at the distal third of the tibia were estimated using beam theory combined with inverse dynamics and musculoskeletal modeling.
Results Intraclass correlation coefficients indicated good-to-excellent repeatability for peak stress values between sessions. Peak anterior and posterior stresses increased after 20 min of prolonged treadmill running and were 15% and 12% greater, respectively, after 40 min of running compared with the start of the run.
Conclusion The hollow elliptical tibial model presented is a repeatable tool that can be utilized to assess within-participant changes in peak tibial stress during running. The increased stresses observed during a prolonged treadmill run may have implications for the development of tibial stress fracture.

Horizontal Crank Position Affects Economy and Upper Limb Kinematics of Recumbent Handcyclists

01-11-2019 – STONE, BENJAMIN; MASON, BARRY S.; WARNER, MARTIN B.; GOOSEY-TOLFREY, VICTORIA L.

Purpose To determine the effects of horizontal crank position on economy and upper limb kinematics in recumbent handcycling.
Methods Fifteen trained handcyclists performed trials at 50% and 70% of their peak aerobic power output (POPeak), determined during a maximal exercise test, in each horizontal crank position. Four horizontal crank positions, 94%, 97%, 100%, and 103% of arm length, were investigated. Horizontal crank positions were defined as the distance between the acromion angle to the center of the handgrip, while the crank arm was parallel to the floor and pointing away from the participant. Economy and upper limb kinematics were calculated during the final minute of each 3-min trial.
Results Horizontal crank position significantly affected handcycling economy at 70% POPeak (P < 0.01) but not at 50% POPeak (P = 0.44). The 97% horizontal crank position (16.0 1.5 m
L·min−1·W−1) was significantly more economical than the 94% (16.7 (1.9) m
L·min−1·W−1) (P = 0.04) and 103% (16.6 (1.7) m
L·min−1·W−1) (P < 0.01) positions. The 100% horizontal crank position (16.2 (1.7) m
L·min−1·W−1) was significantly more economical than the 103% position (P < 0.01). Statistical parametric mapping indicated that an increase in horizontal crank position, from 94% to 103%, caused a significant increase in elbow extension, shoulder flexion, adduction, internal rotation, scapular internal rotation, wrist flexion, clavicle depression and clavicle protraction between 0% and 50% (0°–180°) of the cycle (P < 0.05).
Conclusions Positioning the cranks at 97% to 100% of the athletes’ arm length improved handcycling economy at 70% POPeak as, potentially, the musculature surrounding the joints of the upper limb were in a more favorable position to produce force economically.

Individual Region- and Muscle-specific Hamstring Activity at Different Running Speeds

01-11-2019 – HEGYI, ANDRÁS; GONÇALVES, BASÍLIO A. M.; FINNI, TAIJA; CRONIN, NEIL J.

Introduction Hamstring strain injuries typically occur in the proximal biceps femoris long head (BFlh) at high running speeds. Strain magnitude seems to be the primary determinant of strain injury, and may be regulated by muscle activation. In running, BFlh strain is largest in the proximal region, especially at high speeds. However, region-specific activity has not been examined. This study examined the proximal–distal and intermuscular activity of BFlh and semitendinosus (ST) as a function of increasing running speed.
Methods Thirteen participants ran at steady speeds of 4.1 (slow), 5.4 (moderate), and 6.8 m·s−1 (fast) on a treadmill. Region- and muscle-specific EMG activity were recorded at each speed using high-density EMG, and were normalized to maximal voluntary isometric activity. Muscle–tendon unit lengths were calculated from kinematic recordings. Speed effects, regional, and intermuscular differences were tested with Statistical Parametric Mapping.
Results With increasing running speed, EMG activity increased in all regions of both muscles to a similar extent in the clinically relevant late swing phase. Increases in muscle–tendon unit lengths in late swing as a function of running speed were comparatively small. In fast running, EMG activity was highest in late swing in all regions, and reached 115% ± 20% (proximal region, mean ± 95% confidence limit), 106% ± 11% (middle), and 124% ± 16% (distal) relative to maximal voluntary isometric activity in BFlh. Regional and intermuscular EMG patterns were highly individual, but each individual maintained similar proximal–distal and intermuscular EMG activity patterns across running speeds.
Conclusions Running is associated with highly individual hamstring activity patterns, but these patterns are similar across speeds. It may thus be crucial to implement running at submaximal speeds early after hamstring injury for restoration of normal neuromuscular function.

Ultrasound Does Not Detect Acute Changes in Glycogen in Vastus Lateralis of Man

01-11-2019 – ROUTLEDGE, HARRY E.; BRADLEY, WARREN J.; SHEPHERD, SAM O.; COCKS, MATTHEW; ERSKINE, ROBERT M.; CLOSE, GRAEME L.; MORTON, JAMES P.

Journal Article

Purpose To examine the validity of ultrasound (via cloud-based software that measures pixilation intensity according to a scale of 0–100) to noninvasively assess muscle glycogen in human skeletal muscle.
Methods In study 1, 14 professional male rugby league players competed in an 80-min competitive rugby league game. In study 2 (in a randomized repeated measures design), 16 recreationally active males completed an exhaustive cycling protocol to deplete muscle glycogen followed by 36 h of HIGH or LOW carbohydrate intake (8 g·kg−1 vs 3 g·kg−1 body mass). In both studies, muscle biopsies and ultrasound scans were obtained from the vastus lateralis (at 50% of the muscle length) before and after match play in study 1 and at 36 h after glycogen depletion in study 2.
Results Despite match play reducing (P 0.05) were present between changes in muscle glycogen concentration and changes in ultrasound scores.
Conclusions Data demonstrate that ultrasound (as based on measures of pixilation intensity) is not valid to measure muscle glycogen status within the physiological range (i.e., 200–500 mmol·kg−1 dw) that is applicable to exercise-induced muscle glycogen utilization and postexercise muscle glycogen resynthesis.

Low-Carbohydrate Training Increases Protein Requirements of Endurance Athletes

01-11-2019 – GILLEN, JENNA B.; WEST, DANIEL W. D.; WILLIAMSON, ERIC P.; FUNG, HUGO J. W.; MOORE, DANIEL R.

Journal Article

Introduction Training with low-carbohydrate (CHO) availability enhances markers of aerobic adaptation and has become popular to periodize throughout an endurance-training program. However, exercise-induced amino acid oxidation is increased with low muscle glycogen, which may limit substrate availability for postexercise protein synthesis. We aimed to determine the impact of training with low-CHO availability on estimates of dietary protein requirements.
Methods Eight endurance-trained males (27 ± 4 yr, 75 ± 10 kg, 67 ± 10 m
L·kg body mass−1·min−1) completed two trials matched for energy and macronutrient composition but with differing CHO periodization. In the low-CHO availability trial (LOW), participants consumed 7.8 g CHO−1·kg−1 before evening high-intensity interval training (10 × 5 min at 10-km race pace, 1 min rest) and subsequently withheld CHO postexercise (0.2 g·kg−1). In the high-CHO availability trial (HIGH), participants consumed 3 g CHO·kg−1 during the day before high-intensity interval training, and consumed 5 g CHO·kg−1 that evening to promote muscle glycogen resynthesis. A 10-km run (~80% HRmax) was performed the following morning, fasted (LOW) or 1 h after consuming 1.2 g CHO·kg−1 (HIGH). Whole-body phenylalanine flux and oxidation were determined over 8 h of recovery via oral 13Cphenylalanine ingestion, according to standard indicator amino acid oxidation methodology, while consuming sufficient energy, 7.8 g CHO·kg−1·d−1, and suboptimal protein (0.93 g·kg−1·d−1).
Results Fat oxidation (indirect calorimetry) during the 10-km run was higher in LOW compared with HIGH (0.99 ± 0.35 g·min−1 vs 0.60 ± 0.26 g·min−1, P 0.05) whereas phenylalanine oxidation (reciprocal of protein synthesis) was higher in LOW compared with HIGH (8.8 ± 2.7 μmol·kg−1·h−1 vs 7.9 ± 2.4 μmol·kg−1·h−1, P < 0.05), suggesting a greater amino acid requirement to support rates of whole-body protein synthesis.
Conclusions Our findings suggest that performing endurance exercise with low-CHO availability increases protein requirements of endurance athletes.

Age-associated Performance Decline and Sex Differences in Olympic Weightlifting

01-11-2019 – HUEBNER, MARIANNE; MELTZER, DAVID E.; PERPEROGLOU, ARIS

Journal Article

Introduction The rate of decline in physical performance for women is thought to be faster than that for men at any age in the Masters age classes in weightlifting and other sports. We quantified the age-associated decline in Olympic weightlifting separately for women and men and investigated possible impact of perimenopausal years on the performance decline.
Methods Results from Masters Weightlifting competitions from 1993 to 2018 were compiled from original score sheets and meet results made available by International Weightlifting Federation. Quantile curves were estimated for the age-related performance decline, and confidence intervals (CI) for the fractional performance with reference age 35 yr were calculated. Age-related decline curves were estimated for different periods to examine changes in performance levels.
Results A total of 10,225 performance results for male and female weightlifters age 35 to 90 yr from 71 countries were included in the analysis. At age 40 yr compared with age 35 yr, the fractional performance is 0.947 (95% CI, 0.926–0.975), for men and 0.952 (95% CI. 0.898–0.986) for women while this is reduced to 0.723 (95% CI: 0.651–0.800) at age 60 yr for men and 0.604 (95% CI. 0.543–0.706) for women. Female performance levels before 2000 were worse; however, they have stabilized since 2013.
Conclusions The performances of women weightlifters have improved over the last 25 yr. Thus, previous publications do not reflect current physical capabilities of women. The age-associated performance decline for female weightlifters mirrors the decline for men except for an accelerated decline during a 10-yr period across the age range from late 40s to late 50s thus coinciding with a transition into menopause.

Ischemic Preconditioning Maintains Performance on Two 5-km Time Trials in Hypoxia

01-11-2019 – DA MOTA, GUSTAVO R.; WILLIS, SARAH J.; SOBRAL, NELSON DOS SANTOS; BORRANI, FABIO; BILLAUT, FRANÇOIS; MILLET, GRÉGOIRE P.

Journal Article

Purpose The ergogenic effect of ischemic preconditioning (IPC) on endurance exercise performed in hypoxia remains debated and has never been investigated with successive exercise bouts. Therefore, we evaluated if IPC would provide immediate or delayed effects during two 5-km cycling time trials (TT) separated by ~1 h in hypoxia.
Methods In a counterbalanced randomized crossover design, 13 healthy males (27.5 ± 3.6 yr) performed two maximal cycling 5-km TT separated by ~1 h of recovery (TT1 25 min and TT2 2 h post-IPC/SHAM), preceded by IPC (3 × 5 min occlusion 220 mm Hg/reperfusion 0 mm Hg, bilaterally on thighs) or SHAM (20 mm Hg) at normobaric hypoxia (fraction of inspired oxygen Fi
O2 of 16%). Performance and physiological (i.e., oxyhemoglobin saturation, heart rate, blood lactate, and vastus lateralis oxygenation) parameters were recorded.
Results Time to complete (P = 0.011) 5-km TT and mean power output (P = 0.005) from TT1 to TT2 were worse in SHAM, but not in IPC (P = 0.381/P = 0.360, respectively). There were no differences in time, power output, or physiological variables during the two TT between IPC and SHAM. All muscle oxygenation indices differed (P < 0.001) during the IPC/SHAM with a greater deoxygenation in IPC. During the TT, there was a greater concentration of total hemoglobin in IPC than SHAM (P = 0.047) and greater total hemoglobin in TT1 than TT2. Further, the concentration of oxyhemoglobin was lower during TT2 than TT1 (P = 0.005).
Conclusion In moderate hypoxia, IPC allowed maintaining a higher blood volume during a subsequent maximal exercise, mitigating the performance decrement between two consecutive cycling TT.

Dual-Task Walking Capacity Mediates Tai Ji Quan Impact on Physical and Cognitive Function

01-11-2019 – LI, FUZHONG; HARMER, PETER; CHOU, LI-SHAN

Journal Article

Purpose Emerging evidence indicates exercise training improves mobility and cognition and reduces falls in older adults, but underlying mechanisms are not well understood. This study tested the hypothesis that change in dual-task walking capacity mediates the positive effect of Tai Ji Quan and multimodal exercise on physical performance, activity confidence, global cognition, and falls among community-dwelling older adults at high risk of falling.
Methods We conducted a secondary analysis of a 6-month randomized clinical trial comparing Tai Ji Quan: Moving for Better Balance (TJQMBB) and multimodal exercise to stretching exercise in a sample of 670 adults older than 70 yr who had a history of falls or impaired mobility. Distal outcome measures, ascertained at a 12-month follow-up, were the Short Physical Performance Battery, Activities-Specific Balance Confidence, Montreal Cognitive Assessment, and falls. The mediator hypothesized to account for the intervention effects was dual-task cost estimated by calculating changes in gait speed from single-task to dual-task walking from baseline to the end of intervention.
Results At 12 months, compared with stretching exercise, multimodal exercise significantly improved Short Physical Performance Battery and Activities-Specific Balance Confidence outcomes and reduced the number of falls (P < 0.05). However, it did not lower dual-task cost or mediate the intervention effects on distal outcomes. In contrast, TJQMBB significantly reduced dual-task cost relative to multimodal and stretching exercises (P < 0.05) which in turn resulted in improvements in lower-extremity physical performance, activity confidence, global cognitive function, and reductions in falls (P < 0.05) during follow-up.
Conclusions Enhanced dual-task walking capacity as a result of Tai Ji Quan training mediated improvements in physical and cognitive outcomes in older adults at high risk of falling.

Sedentarism, Physical Activity, Steps, and Neurotrophic Factors in Obese Children

01-11-2019 – MORA-GONZALEZ, JOSE; MIGUELES, JAIRO H.; ESTEBAN-CORNEJO, IRENE; CADENAS-SANCHEZ, CRISTINA; PASTOR-VILLAESCUSA, BELÉN; MOLINA-GARCÍA, PABLO; RODRIGUEZ-AYLLON, MARÍA; RICO, MARÍA C.; GIL, ANGEL; AGUILERA, CONCEPCIÓN M.; ESCOLANO-MARGARIT, MARÍA VICTORIA; GEJL, ANNE KAER; ANDERSEN, LARS BO; CATENA, ANDRÉS; ORTEGA, FRANCISCO B.

Purpose This study aimed to examine the associations of sedentary time, physical activity (PA) and step-related behaviors with neurotrophic growth factors.
Methods A total of 97 children with overweight/obesity age 8 to 11 yr participated in this study. Sedentary time, PA, and steps were measured by GT3X+ accelerometers in hip and nondominant wrist. Estimates of light, moderate, vigorous, and moderate-to-vigorous PA (MVPA) were obtained. Steps per daytime, peak 60-, 30-, and 1-min cadence were computed. The time accumulated (min·d−1) in different cadence bands of steps was also computed from hip accelerometer. Plasma levels of brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and insulin growth factor-1 (IGF-1) were determined by the XMap technology (Luminex IS 100/200 system, Luminex Corporation, Austin, TX).
Results Light PA, moderate PA, MVPA, and the peak 60-min cadence were positively related with BDNF concentrations (all P 0.05). The associations of light PA with BDNF and VEGF disappeared (all P > 0.05) after performing analyses with nondominant wrist-placement data. However, moderate PA and MVPA remained significantly associated with BDNF (both P < 0.05). The time accumulated in cadence bands of 40 to 59 steps per day and 60 to 79 steps per day (i.e., walking at slow pace) was positively associated with plasma BDNF (all P < 0.05).
Conclusions In conclusion, PA is positively related to plasma BDNF, whereas no relationship was observed for VEGF or IGF-1. Higher amounts of time spent in slow walking cadence bands could increment BDNF levels. Exercise-based randomized controlled trials in children with overweight/obesity should be carried out to better understand the influence of PA behaviors on the neurotrophic factors.

Motor Strategies Learned during Pain Are Sustained upon Pain-free Reexposure to Task

01-11-2019 – SALOMONI, SAURO E.; MARINOVIC, WELBER; CARROLL, TIMOTHY J.; HODGES, PAUL W.

Journal Article

Introduction Pain affects movement planning and execution, and may interfere with the ability to learn new motor skills. Variations among previous studies suggest task-specific effects of pain on the initial acquisition and subsequent retention of motor strategies.
Methods The present study assessed how acute pain in the anterior deltoid muscle affects movement accuracy of fast arm-reaching movements during force field perturbations and upon immediate pain-free repetition of the same task.
Results Despite having slower initial rate of improvement, individuals who experienced pain during training achieved the same final performance as pain-free controls. However, pain altered the strategy of muscle activation adopted to perform the task, which involved less activity of the shoulder and arm muscles. Strikingly, motor strategies developed during the first exposure to the force field were retained upon reexposure to the same perturbation after resolution of pain.
Conclusions Although reduced muscle activation may be interpreted as metabolically efficient, it reduces joint stability and can have negative consequences for joint integrity. These results demonstrate that alternative motor strategies developed in the presence of pain can be maintained when training is resumed after resolution of pain. This effect could have deleterious consequences if it applies when learning motor skills in sports training and rehabilitation.

Delayed-Onset Muscle Soreness and Topical Analgesic Alter Corticospinal Excitability of the Biceps Brachii

01-11-2019 – STEFANELLI, LUCAS; LOCKYER, EVAN J.; COLLINS, BRANDON W.; SNOW, NICHOLAS J.; CROCKER, JULIE; KENT, CHRISTOPHER; POWER, KEVIN E.; BUTTON, DUANE C.

Journal Article

Introduction The interactive effect of delayed-onset muscle soreness (DOMS) and a topical analgesic on corticospinal excitability was investigated.
Methods Thirty-two participants completed Experiments A (no DOMS) and B (DOMS). For each experiment, participants were randomly assigned to two groups: 1) topical analgesic gel (topical analgesic, n = 8), or 2) placebo gel (placebo, n = 8) group. Before the application of gel (pregel), as well as 5, 15, 30, and 45 min postgel, motor-evoked potential (MEP) area, latency, and silent period, as well as cervicomedullary MEP and maximal compound motor unit action potential areas and latencies were measured. In addition, pressure–pain threshold (PPT) was measured pre-DOMS and at the same timepoints in experiment B.
Results In experiment A, neither group showed a significant change for any outcome measure. In experiment B, both groups exhibited a significant decrease in PPT from pre-DOMS to pregel. After the application of topical analgesic, but not placebo, there was a significant increase in PPT at 45 min postgel, respectively, compared with pregel and a main effect of time for the silent period to increase compared with pregel. Participants with DOMS had reduced MEP and cervicomedullary MEP areas and increased corticospinal silent periods compared with those who did not have DOMS.
Conclusions These findings suggest that DOMS reduced corticospinal excitability and after the administration of menthol-based topical analgesic, there was a reduction in pain, which was accompanied by increased corticospinal inhibition.

Supraspinal Control of Recurrent Inhibition during Anisometric Contractions

01-11-2019 – BARRUÉ-BELOU, SIMON; MARQUE, PHILIPPE; DUCLAY, JULIEN

Journal Article

Purpose Increase in recurrent inhibition was observed during eccentric compared with isometric and concentric maximal voluntary contractions but the neural mechanisms involved in this specific control of the Renshaw cell activity are unknown. This study was designed to investigate the supraspinal control of the recurrent inhibition during anisometric contractions of the plantar flexor muscles.
Methods To that purpose, the paired Hoffmann-reflex (H-reflex) technique permitted to assess changes in homonymous recurrent pathway by comparing the modulations of test and conditioning H-reflexes (H′ and H1, respectively) in the soleus (SOL) muscle during maximal and submaximal isometric, concentric and eccentric contractions. Submaximal contraction intensity was set at 50% of the SOL electromyographic activity recorded during maximal isometric contraction. Fourteen volunteer subjects participated in an experimental session designed to assess the activity of the recurrent inhibition pathway.
Results The results indicate that the amplitude of H1 normalized to the maximal M-wave were similar (P > 0.05) regardless of the muscle contraction type and intensity. Whatever the contraction intensity, the ratio between H′ and H1 amplitudes was significantly decreased (P < 0.05) during eccentric compared with isometric and concentric contractions. Furthermore, this ratio was significantly smaller (P < 0.05) during submaximal compared with maximal contractions whatever the muscle contraction type.
Conclusion Together, the current results confirm the supraspinal control of the Renshaw cell activity when muscle contraction intensity is modulated and show that this control remains similar for isometric, concentric and eccentric contractions. Data further suggest that recurrent inhibition pathway may serve as variable gain regulator at motoneuronal level to improve resolution in the control of motor output for the SOL during eccentric contractions.

Data-informed Intervention Improves Football Technique and Reduces Head Impacts

01-11-2019 – CHAMPAGNE, ALLEN A.; DISTEFANO, VINCENT; BOULANGER, MARIE-MICHELLE; MAGEE, BLAIRE; COVERDALE, NICOLE S.; GALLUCCI, DANIEL; GUSKIEWICZ, KEVIN; COOK, DOUGLAS J.

Journal Article

Introduction Although sport participation is a key contributor to the physical and mental health of children and youth, exposure to subconcussive head impacts in football has raised concerns about safety for athletes.
Purpose To demonstrate the efficacy of incorporating targeted football drills into a team’s practice routine with the goal of improving players’ technique and reduce exposure to subconcussive head impacts.
Methods Seventy high school football players (age, 16.4 ± 1.1 yr) were tested PRE season using a sport-specific functional assessment. Results from the testing were used to inform the design of a prepractice intervention aimed at improving tackling and blocking techniques while reducing exposure to head impacts. The assessment included drills which evaluated the players’ ability to safely tackle, and block while simulating game-like situations. Testing was repeated at MID season (internal control) without an intervention, and again at POST season (experimental), after introduction of the prepractice intervention between these timepoints, administered twice weekly. All testing sessions were recorded, and subsequently reviewed by trained graders based on selected criteria defined by football coaches. A subset of 19 participants wore in-helmet accelerometers to assess the effectiveness of the intervention in decreasing head impacts during practice.
Results Significant improvements in blocking and tackling techniques were observed after the introduction of the intervention (P 15g) per practice was significantly reduced by ~30% after 1 month of training.
Conclusion Our results suggest that data-informed methods can be used to improve coaching practices and promote safer play, which can have a positive public health impact moving forward.

Exercise Guidelines for Cancer Survivors: Consensus Statement from International Multidisciplinary Roundtable

01-11-2019 – CAMPBELL, KRISTIN L.; WINTERS-STONE, KERRI M.; WISKEMANN, JOACHIM; MAY, ANNE M.; SCHWARTZ, ANNA L.; COURNEYA, KERRY S.; ZUCKER, DAVID S.; MATTHEWS, CHARLES E.; LIGIBEL, JENNIFER A.; GERBER, LYNN H.; MORRIS, G. STEPHEN; PATEL, ALPA V.; HUE, TRISHA F.; PERNA, FRANK M.; SCHMITZ, KATHRYN H.

Purpose The number of cancer survivors worldwide is growing, with over 15.5 million cancer survivors in the United States alone—a figure expected to double in the coming decades. Cancer survivors face unique health challenges as a result of their cancer diagnosis and the impact of treatments on their physical and mental well-being. For example, cancer survivors often experience declines in physical functioning and quality of life while facing an increased risk of cancer recurrence and all-cause mortality compared with persons without cancer. The 2010 American College of Sports Medicine Roundtable was among the first reports to conclude that cancer survivors could safely engage in enough exercise training to improve physical fitness and restore physical functioning, enhance quality of life, and mitigate cancer-related fatigue.
Methods A second Roundtable was convened in 2018 to advance exercise recommendations beyond public health guidelines and toward prescriptive programs specific to cancer type, treatments, and/or outcomes.
Results Overall findings retained the conclusions that exercise training and testing were generally safe for cancer survivors and that every survivor should “avoid inactivity.” Enough evidence was available to conclude that specific doses of aerobic, combined aerobic plus resistance training, and/or resistance training could improve common cancer-related health outcomes, including anxiety, depressive symptoms, fatigue, physical functioning, and health-related quality of life. Implications for other outcomes, such as peripheral neuropathy and cognitive functioning, remain uncertain.
Conclusions The proposed recommendations should serve as a guide for the fitness and health care professional working with cancer survivors. More research is needed to fill remaining gaps in knowledge to better serve cancer survivors, as well as fitness and health care professionals, to improve clinical practice.

American College of Sports Medicine Roundtable Report on Physical Activity, Sedentary Behavior, and Cancer Prevention and Control

01-11-2019 – PATEL, ALPA V.; FRIEDENREICH, CHRISTINE M.; MOORE, STEVEN C.; HAYES, SANDRA C.; SILVER, JULIE K.; CAMPBELL, KRISTIN L.; WINTERS-STONE, KERRI; GERBER, LYNN H.; GEORGE, STEPHANIE M.; FULTON, JANET E.; DENLINGER, CRYSTAL; MORRIS, G. STEPHEN; HUE, TRISHA; SCHMITZ, KATHRYN H.; MATTHEWS, CHARLES E.

Introduction The American College of Sports Medicine convened an International Multidisciplinary Roundtable on Exercise and Cancer in March 2018 to evaluate and translate the evidence linking physical activity and cancer prevention, treatment, and control. This article discusses findings from the Roundtable in relation to the biologic and epidemiologic evidence for the role of physical activity in cancer prevention and survival.
Results The evidence supports that there are a number of biologically plausible mechanisms, whereby physical activity can influence cancer risk, and that physical activity is beneficial for the prevention of several types of cancer including breast, colon, endometrial, kidney, bladder, esophageal, and stomach. Minimizing time spent in sedentary behavior may also lower risk of endometrial, colon and lung cancers. Conversely, physical activity is associated with higher risk of melanoma, a serious form of skin cancer. Further, physical activity before and after a cancer diagnosis is also likely to be relevant for improved survival for those diagnosed with breast and colon cancer; with data suggesting that postdiagnosis physical activity provides greater mortality benefits than prediagnosis physical activity.
Conclusions Collectively, there is consistent, compelling evidence that physical activity plays a role in preventing many types of cancer and for improving longevity among cancer survivors, although the evidence related to higher risk of melanoma demonstrates the importance of sun safe practices while being physically active. Together, these findings underscore the importance of physical activity in cancer prevention and control. Fitness and public health professionals and health care providers worldwide are encouraged to spread the message to the general population and cancer survivors to be physically active as their age, abilities, and cancer status will allow.

Assessment of Na+/K+ ATPase Activity in Small Rodent and Human Skeletal Muscle Samples

01-11-2019 – JANNAS-VELA, SEBASTIAN; BROWNELL, STUART; PETRICK, HEATHER L.; HEIGENHAUSER, GEORGE J. F.; SPRIET, LAWRENCE L.; HOLLOWAY, GRAHAM P.

Introduction In skeletal muscle, the Na+/K+ ATPase (NKA) plays essential roles in processes linked to muscle contraction, fatigue, and energy metabolism; however, very little information exists regarding the regulation of NKA activity. The scarcity of information regarding NKA function in skeletal muscle likely stems from methodological constraints, as NKA contributes minimally to total cellular ATP utilization, and therefore contamination from other ATPases prevents the assessment of NKA activity in muscle homogenates. Here we introduce a method that improves accuracy and feasibility for the determination of NKA activity in small rodent muscle samples (5–10 mg) and in human skeletal muscle.
Methods Skeletal muscle homogenates from mice (n = 6) and humans (n = 3) were used to measure NKA and sarcoplasmic reticulum Ca2+ ATPase (SERCA) activities with the addition of specific ATPase inhibitors to minimize “background noise.”Results We observed that myosin ATPase activity was the major interfering factor for estimation of NKA activity in skeletal muscle homogenates, as the addition of 25 μM of blebbistatin, a specific myosin ATPase inhibitor, considerably minimized “background noise” (threefold) and enabled the determination of NKA maximal activity with values three times higher than previously reported. The specificity of the assay was demonstrated after the addition of 2 m
M ouabain, which completely inhibited NKA. On the other hand, the addition of blebbistatin did not affect the ability to measure SERCA function. The coefficient of variation for NKA and SERCA assays were 6.2% and 4.4%, respectively.
Conclusion The present study has improved the methodology to determine NKA activity. We further show the feasibility of measuring NKA and SERCA activities from a common muscle homogenate. This methodology is expected to aid in our long-term understanding of how NKA affects skeletal muscle metabolic homeostasis and contractile function in diverse situations.

Activity Intensity, Volume, and Norms: Utility and Interpretation of Accelerometer Metrics

01-11-2019 – ROWLANDS, ALEX V.; FAIRCLOUGH, STUART J.; YATES, TOM; EDWARDSON, CHARLOTTE L.; DAVIES, MELANIE; MUNIR, FEHMIDAH; KHUNTI, KAMLESH; STILES, VICTORIA H.

Journal Article

Purpose The physical activity profile can be described from accelerometer data using two population-independent metrics: average acceleration (ACC, volume) and intensity gradient (IG, intensity). This article aims 1) to demonstrate how these metrics can be used to investigate the relative contributions of volume and intensity of physical activity for a range of health markers across data sets and 2) to illustrate the future potential of the metrics for generation of age and sex-specific percentile norms.
Methods Secondary data analyses were conducted on five diverse data sets using wrist-worn accelerometers (Acti
Graph/GENEActiv/Axivity): children (n = 145), adolescent girls (n = 1669), office workers (n = 114), premenopausal (n = 1218) and postmenopausal (n = 1316) women, and adults with type 2 diabetes (n = 475). Open-source software (GGIR) was used to generate ACC and IG. Health markers were (a) z
BMI (children), (b) %fat (adolescent girls and adults), (c) bone health (pre- and postmenopausal women), and (d) physical function (adults with type 2 diabetes).
Results Multiple regression analyses showed that IG, but not ACC, was independently associated with z
BMI/%fat in children and adolescents. In adults, associations were stronger and the effects of ACC and IG were additive. For bone health and physical function, interactions showed associations were strongest if IG was high, largely irrespective of ACC. Exemplar illustrative percentile “norms” showed the expected age-related decline in physical activity, with greater drops in IG across age than ACC.
Conclusion The ACC and the IG accelerometer metrics facilitate the investigation of whether volume and intensity of physical activity have independent, additive, or interactive effects on health markers. In future studies, the adoption of data-driven metrics would facilitate the generation of age- and sex-specific norms that would be beneficial to researchers.

Regarding High-Intensity Interval Training and Left Ventricular Mechanics

01-11-2019 – Stöhr, Eric J.; Balmain, Bryce N.; Sabapathy, Surendran

No abstract available

Response

01-11-2019 – Wang, Jong-Shyan

No abstract available

Thermoregulation following Spinal Cord Injury: Theory and Fact

01-11-2019 – Zhang, Yang

No abstract available

Response

01-11-2019 – Forsyth, Peta; Miller, Joanna; Pumpa, Kate; Thompson, Kevin G.; Jay, Ollie

No abstract available

Challenging Neuropathic Pain Syndromes: Evaluation and Evidence-Based Treatment

01-11-2019 –

No abstract available

Upper Extremity Injuries in Young Athletes

01-11-2019 –

No abstract available

Ibuprofen before Exercise Does Not Prevent Cortical Bone Adaptations to Training—Corrigendum

01-11-2019 –

No abstract available