Pulmonary and respiratory muscle function in response to 10 marathons in 10 days

Purpose: Marathon and ultramarathon provoke respiratory muscle fatigue and pulmonary dysfunction; nevertheless, it is unknown how the respiratory system responds to multiple, consecutive days of endurance exercise. Methods: Nine trained individuals (six male) contested 10 marathons in 10 consecutive days. Respiratory muscle strength (maximum static inspiratory and expiratory mouth-pressures), pulmonary function (spirometry), perceptual ratings of respiratory muscle soreness (Visual Analogue Scale), breathlessness (dyspnea, modified Borg CR10 scale), and symptoms of Upper Respiratory Tract Infection (URTI), were assessed before and after marathons on days 1, 4, 7, and 10. Results: Group mean time for 10 marathons was 276 ± 35 min. Relative to pre-challenge baseline (159 ± 32 cmH2O), MEP was reduced after day 1 (136 ± 31 cmH2O, p = 0.017), day 7 (138 ± 42 cmH2O, p = 0.035), and day 10 (130 ± 41 cmH2O, p = 0.008). There was no change in pre-marathon MEP across days 1, 4, 7, or 10 (p > 0.05). Pre-marathon forced vital capacity was significantly diminished at day 4 (4.74 ± 1.09 versus 4.56 ± 1.09 L, p = 0.035), remaining below baseline at day 7 (p = 0.045) and day 10 (p = 0.015). There were no changes in FEV1, FEV1/FVC, PEF, MIP, or respiratory perceptions during the course of the challenge (p > 0.05). In the 15-day post-challenge period, 5/9 (56%) runners reported symptoms of URTI, relative to 1/9 (11%) pre-challenge. Conclusions: Single-stage marathon provokes acute expiratory muscle fatigue which may have implications for health and/or performance, but 10 consecutive days of marathon running does not elicit cumulative (chronic) changes in respiratory function or perceptions of dyspnea. These data allude to the robustness of the healthy respiratory system

Dynamic loading and kinematics analysis of vertical jump based on different forefoot morphology

PURPOSE: This study examined differences in ankle motion and plantar pressure between habitually barefoot male (HBM) and habitually shod male (HSM) during vertical jump. METHODS: Eighteen habitually barefoot males and twenty habitually shod males volunteered to join the test. Distance between hallux and second toe was measured with Easy-Foot-Scan. Plantar pressure and ankle kinematics were measured with EMED force platform and Vicon motion analysis system respectively. T test was taken to analyse the significant differences using Stata 12.0 software. RESULTS: The distance between hallux and other toes in HBM was greater than it in HSM. HBM showed larger plantar loading under hallux and medial forefoot, while HSM showed lager plantar loading under medial and central forefoot. HBM had smaller ankle plantarflexion, eversion and external rotation than HSM. CONCLUSION: Findings of this study provide basic information for further studies on different hallux/toe function in motion control between habitually shod and barefoot populations

Effects of Caffeine Supplementation on Performance in Ball Games

This is a post-peer-review, pre-copyedit version of an article published in Sports Medicine. The final authenticated version is available online at: http://dx.doi.org/10.1007/s40279-017-0763-6.Although a large body of evidence exists documenting the ergogenic properties of caffeine, most studies have focused on endurance performance. However, findings from endurance sports cannot be generalized to performance in ball games where, apart from having a high level of endurance, successful athletic performances require a combination of physiological, technical and cognitive capabilities. The purpose of this review was to critically evaluate studies that have examined the effect of a single dose of caffeine in isolation on one or more of the following performance measures: total distance, sprint performance, agility, vertical jump performance and accuracy in ball games. Searches of three major databases resulted in 19 studies (invasion games: 13; net-barrier games: 6) that evaluated the acute effects of caffeine on human participants, provided the caffeine dose administered, and included a ball games specific task or simulated match. Improvements in sprint performance were observed in 8 of 10 studies (80%), and vertical jump in 7 of 8 studies (88%). Equivocal results were reported for distance covered, agility and accuracy. Minor side effects were reported in 4 of 19 studies reviewed. Pre-exercise caffeine ingestion between 3.0 and 6.0 mg/kg of body mass appears to be a safe ergogenic aid for athletes in ball games. However, the efficacy of caffeine varies depending on various factors, including, but not limited to, the nature of the game, physical status and caffeine habituation. More research is warranted to clarify the effects of caffeine on performance measures unique to ball games, such as agility and accuracy. It is essential that athletes, coaches and practitioners evaluate the risk-benefit ratio of caffeine ingestion strategies on an individual case-by-case basis