Sport and Exercise

Career Performance Progressions of Junior and Senior Elite Track and Field Athletes Abstract Purpose To compare and assess differences in the career performance progressions of elite junior and Olympic track and field athletes. Methods Annual best performances from top 8 men and women (e.g. finalists) in track and field events at the 2000 World Junior Championships (junior cohort) and the 2000 Olympic Games (Olympic cohort) were examined. Annual bests of these finalists were tracked each year from select groups: sprints (100 m, 200 m), distance (1500 m, 5000 m), jumps (long jump, high jump), throws (discus, shot put). Age of best lifetime performance, age of final posted performance, and improvement from junior-age best to lifetime best performance were compared between groups. Results Olympic finalists achieved lifetime best performances at later ages than junior finalists [26.0 ± 4.0 years vs. 21.1 ± 3.5 years; age difference 90% CI (3.7–5.2 years), P < 0.001], and this significant age difference between cohorts was found within all four groups. Olympic finalists improved from under-20 best to lifetime best more so than junior finalists [6.1 ± 4.8% vs. 2.5 ± 2.3%; Age difference 90% CI (2.5–4.8%), P < 0.001]. Of 130 junior finalists, 54 did not improve after age 19, while 19 of 128 Olympic finalists posted no improvement after age 19. Conclusion The data suggest that these two populations have different career performance progressions and challenge the notion that achieving elite success as a junior athlete is a prerequisite for the same success at the senior level.

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Commentary on Wang Y et al. "An Overview of Non-exercise Estimated Cardiorespiratory Fitness: Estimation Equations, Cross-Validation and Application"

Passive Strategies for the Prevention of Muscle Wasting During Recovery from Sports Injuries Abstract Background Recovery from sport injuries commonly involves a muscle disuse situation (i.e., reduction in physical activity levels sometimes preceded by joint immobilization) with subsequent negative effects on muscle mass and function. Purpose To summarize the current body of knowledge on the effectiveness of different physical strategies that are currently available to mitigate the negative effects of muscle disuse during recovery from sports injury. Methods A narrative review was conducted to summarize the information available on neuromuscular electrical stimulation (NMES), blood flow restriction (BFR) and vibration intervention. Results The concomitant application of BFR and low-intensity exercise has shown promising results in the prevention of disuse-induced muscle atrophy. Some benefits might also be obtained with BFR alone (i.e., with no exercise), but evidence is still inconclusive. NMES, which can be applied both passively and synchronously with exercise, can also attenuate most of the negative changes associated with disuse periods. In turn, the mechanical stimulus elicited by vibration seems effective to reduce the loss of bone mineral density that accompanies muscle disuse and could also provide some benefits at the muscle tissue level. Conclusions Different physical strategies are available to attenuate disuse-induced negative consequences during recovery from injury. These interventions can be applied passively, which makes them feasible during the first stages of the recovery. However, it would be advisable to apply these strategies in conjunction with low-intensity voluntary exercise as soon as this is feasible.

Exercise Against Aging: Darwinian Natural Selection Among Fit and Unfit Cells Inside Human Body Abstract Exercise inevitably induces damages and triggers a brief inflammation in challenged tissues of the human body. Nevertheless, regular exercise is associated with improved physical fitness and lower all-cause mortality among adults in a dose-dependent manner. The paradox between destructive nature of exercise and its anti-aging benefit can be best explained by decreasing aged cell population of the human body in a Darwinian natural selection fashion, resulting in tissue renewal. In this concept, the unfit-to-fit cell ratio of a multicellular system increases during growth (expansion of cell population and size) and decreases after exercise challenges. Inflammation serves as an innate mechanism to recognize cells in danger and triggers clearance mechanism to eliminate unhealthy cells followed by regeneration. A recent finding of decreased p16INK4a+ senescent cells together with CD68+ macrophage infiltration in human skeletal muscle after resistance exercise supports this concept. The senescent cells are mostly stem cells located in capillaries surrounding myofibers, functioning to replace short-lived endothelial cells. They can be found in young men aged 20–25 years. In this context, exercise controls weight gain (i.e. cell number and size) and decrease senescent cell proportion in capillaries of the human body, providing benefits in physical fitness and increasing life expectancy.

Resistance Exercise Increases the Regulation of Skeletal Muscle FSTL1 Consequently Improving Cardiac Angiogenesis in Rats with Myocardial Infarctions Abstract Purpose The aim of this study was to investigate whether skeletal muscle-derived follistatin-like 1 (FSTL1) reaches the heart and exerts the angiogenetic function in rats suffering myocardial infarctions (MI) after exercise intervention. Methods Forty-eight male adult Sprague–Dawley rats were randomly divided into four groups. MI was provoked by ligation of left anterior descending coronary artery. MI rats underwent adeno-associated virus injection of FST1 in tibialis anterior muscle and 4 weeks of resistance exercise via a tail-suspended incremental weight-climbing method (0–75% body weight, daily load increased by 10%; 1 h/day, 5 day/w). Heart function was evaluated by hemodynamics including LVSP, LVEDP and ± dP/dt max; the cross-sectional area of muscle cells and myocardium fibrosis were analyzed by DiI and Masson's staining, respectively; the FSTL1 expression, endothelial cell proliferation and angiogenesis were visualized by immunofluorescence staining; and protein expression was quantified by Western blotting. Results Resistance exercise reverted MI-induced skeletal muscle atrophy, increased muscle FSTL1 expression and stimulated skeletal muscle derived FSTL1 entering into the MI heart via blood circulation. The overexpression of skeletal muscle FSTL1 improved myocardial endothelial cell proliferation, increased small vessel density in the fibrotic border, inhibited myocardial fibrosis and improved heart function in the MI rats after the exercise intervention. Meanwhile, DIP2A-PI3K-Akt-mTOR, Erk1/2 and TGFβ-Smad2/3 pathways were activated in the myocardium. Conclusion Resistance exercise stimulates skeletal muscle derived FSTL1 to reach the myocardium which makes a positive contribution to cardioprotection in MI rat.

Relationships Between Estimated Hourly Energy Balance and Body Composition in Professional Cheerleaders Abstract Purpose We sought to describe and examine the interrelationships between energy intake, body composition, and estimated energy balance. Methods Using self-reported hourly food intake and formula-based energy expenditure (EE) protocols, 19 female professional cheerleaders (mean age 25.4 years) were assessed to obtain energy balance (EB) for a typical training day. Energy intake (EI) was predicted using the USDA Food Composition Database SR27, and EE was predicted using the Harris-Benedict equation plus a MET-based relative intensity activity scale. Body composition was predicted using a multi-current, 8-mode segmental bioelectrical impedance analysis system. Hourly and daily EB was calculated from EI and EE data. Results Subjects reported a 24 h EI significantly below (P < 0.001) the unadjusted predicted energy requirement (1482 kcal vs. 2199 kcal, respectively), resulting in an average negative net EB of − 720 kcal. Carbohydrate intake was significantly below the minimum recommended level (3.1 g/kg vs. 6 g/kg, P < 0.001) while protein and fat intakes met the recommended levels. Higher fat intake (g/kg) was significantly associated with a higher EI kcal/kg (r = 0.726; P < 0.001), which was significantly associated (r = − 0.55; P = 0.01) with a lower body fat percent (BF%). Using the median of BF% (20.9) as the cut point, participants with fewer hours in a negative EB had lower BF% (P = 0.043) and those with lower BF% spent more time in an EB of ± 300 kcal (P = 0.013). Conclusions These athletes reported low energy intakes that resulted in large EB deficits and/or more hours in a negative EB, which could be counterproductive for achieving a lean body composition overtime.

Experimental Investigation of the Effects of Acute Exercise on Real-World Ecological Memory Abstract Purpose To evaluate the effects of acute moderate-intensity exercise on ecological memory, as assessed from a face-name memory task. Methods A two-arm, parallel-group, randomized controlled intervention was employed. Participants (N = 40; Mage = 20.8 years) were randomized into a seated control task or a bout of acute moderate-intensity treadmill exercise (15-min). Thereafter, participants completed a 3-phase face-name memory task, involving a study phase and two test phases (immediate and delayed recall, with the delay occurring 15 min after the immediate recall). Results For the immediate memory recall, the mean (SD) scores for the exercise and control conditions, respectively, were 6.60 (2.5) and 6.20 (2.5). For the 15-min delayed assessment, the respective scores were 6.25 (2.6) and 5.75 (1.9). There was a significant main effect for time (F = 4.06, P = 0.05, \( \eta^{2}_{{p}} \)  = 0.10). However, there were no main effects for group (F = 0.33, P = 0.56, \( \eta^{2}_{{p}} \)  = 0.01) or time by group interactions (F = 0.12, P = 0.72, \( \eta^{2}_{{p}} \)  = 0.003). Conclusions Despite the exercise group having slightly higher immediate and delayed face-name memory scores, we did not observe robust evidence of acute exercise enhancing face-name memory performance.

Acute Effects of Stretching on Flexibility and Performance: A Narrative Review Abstract Passive and active stretching techniques have been shown to increase both chronic and acute range of motion (ROM). Acute ROM improvements can be countered by decreases in muscle performance, primarily after prolonged static stretching (SS) and proprioceptive neuromuscular facilitation (PNF) techniques when not incorporated into a full warm up procedure. In contrast, ballistic stretching and dynamic stretching techniques typically induce either an increase or no change in muscular force and power. This review explores studies that have investigated stretching responses on ROM, muscle functionality and performance. Collectively, the literature demonstrates that prolonged acute SS and PNF stretching can elicit the greatest changes in flexibility, but without additional dynamic activities (i.e. full warm up) can induce neuromuscular force and power output impairments, while increasing ROM and some sports specific performance. Muscle response to stretching may be determined by the manipulation of confounding variables such as duration, population, volume, test specificity and frequency. An increased dosage of some of these variables during stretching in isolation, augments ROM increases while attenuating muscle force output, except for stretching intensity which may lead to similar responses. Populations with high flexibility may have positive effects from stretching when tested on their sport specific performance, while general population may suffer greater negative effects. Not controlling these variables during stretching protocols may lead to misleading information regarding its effects on muscle performance.

Longitudinal Changes in Sarcopenia Criteria in Older Men with Low Skeletal Muscle Mass Index: A 2-Year Observational Study Abstract Purpose Declines in muscle mass and function are inevitable during the aging process. However, what is the "normal age appropriate" decline of muscle mass and function? Further, is this decline uniform for muscle mass versus functions or between different functional abilities? Using recognized Sarcopenia criteria [i.e. skeletal muscle mass index (SMI) defined as appendicular skeletal muscle mass/height (kg/m2), handgrip strength, gait velocity], the aim of the present project was to determine corresponding changes in community-dwelling men 70 years+ with low SMI over a 2-year period. Methods One hundred and seventy-seven (177) men within the lowest SMI quartile of a recent epidemiologic study (n = 965) were included in the 2-year follow-up analysis. Muscle mass was determined via direct-segmental, multi-frequency Bio-Impedance-Analysis, handgrip strength was tested with a Jamar hand-dynamometer and habitual gait speed was assessed with photo sensors applying the 10 m protocol. Results SMI, handgrip strength and gait velocity all declined significantly ( P< 0.001; effect size, d′ 0.39–1.17), however, with significantly higher reductions (P< 0.001) in functional compared with morphologic Sarcopenia criteria (P ≤ 0.006). Less expected, handgrip strength featured a fourfold higher decline compared with gait velocity (− 12.8 ± 10.9% versus − 3.5 ± 9.0%). Conclusion We provided evidence for significant non-uniform changes of Sarcopenia criteria in a cohort of community dwelling men 70 years+ with low SMI. We doubt that this result might be a particularity of the selected cohort; however, studies with other (older) cohorts should address this issue in more depth. Of practical relevance, our data further give implications for the prioritization of interventions that address Sarcopenia criteria in older community-dwelling men.

Alexandros Sfakianakis
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