Despite extensive data regarding the demands of playing basketball, the relative importance of factors that cause fatigue and muscle potentiation has been explored only tentatively and remains unclear. The aim of this experimental field study was to assess changes in leg muscle power and relate these changes to body temperature modifications and indices of exercise-induced muscle damage in response to a simulated basketball game. College-level male basketball players (n=10) were divided into two teams to play a simulated basketball game. Ten-meter sprint and vertical counter-movement jump tests, core body temperature and creatine-kinase activity were measured within 48 h after the game. The participants’ body temperatures increased after a warm-up (1.9%, p<0.05), continued to increase throughout the game, and reached 39.4 ± 0.4°C after the fourth quarter (p<0.05). The increase in temperature during the warm-up was accompanied by an improvement in the 10-meter sprint time (5.5%, p<0.05) and jump height (3.8%, p200%, p30%, p<0.05) after the game, indicating damage to the players’ muscles. The basketball players’ sprint and jump performance appear to be at least in part associated with body temperature changes, which might contribute to counteract fatigue during the larger part of a basketball game.

Sprint interval training (SIT) has emerged as a time-efficient training regimen for young individuals. Here, we studied whether SIT is effective also in elderly individuals and whether the training response was affected by treatment with the antioxidants vitamin C and E. Recreationally active elderly (mean age 65) men received either vitamin C (1 g/day) and vitamin E (235 mg/day) or placebo. Training consisted of nine SIT sessions (three sessions/week for three weeks of 4-6 repetitions of 30-s all-out cycling sprints) interposed by 4 min rest. Vastus lateralis muscle biopsies were taken before, 1 h after, and 24 h after the first and last SIT sessions. At the end of the three weeks of training, SIT-induced changes in relative mRNA expression of reactive oxygen/nitrogen species (ROS)- and mitochondria-related proteins, inflammatory mediators, and the sarcoplasmic reticulum Ca²⁺ channel, the ryanodine receptor 1 (RyR1), were blunted in the vitamin treated group. Western blots frequently showed a major (>50%) decrease in the full-length expression of RyR1 24 h after SIT sessions; in the trained state, vitamin treatment seemed to provide protection against this severe RyR1 modification. Power at exhaustion during an incremental cycling test was increased by ~5% at the end of the training period, whereas maximal oxygen uptake remained unchanged; vitamin treatment did not affect these measures. In conclusion, treatment with the antioxidants vitamin C and E blunts SIT-induced cellular signaling in skeletal muscle of elderly individuals, while the present training regimen was too short or too intense for the changes in signaling to be translated into a clear-cut change in physical performance.

Context: Nerves or fascia may limit motion in young soccer players, thereby contributing to frequent hamstring injuries. Nerve gliding exercises and self-myofascial release techniques may enhance the range of motion. Objective: The aim of this study was to compare the acute effect of foam rolling (FR) and neurodynamic nerve gliding (NDNG) on hamstring flexibility, passive stiffness, viscoelasticity and proprioception during the warm-up of soccer players. Design: Crossover study design. Setting: Research laboratory. Participants: Fifteen male soccer players on the same team (age 18.0 ± 1.4 years, body mass 76.9 ± 7.8 kg, height 183 ± 6 cm). Intervention: FR and NDNG included six sets of 45 s with 15 s rest between each set. Over a two-week period subjects performed NDNG and FR on two separate occasions. Main Outcome Measure(s): Hip flexion angle (SLR), knee extension range of motion (ROM), knee joint position sense (AKJPS), hamstring passive resistance torque (PRT), stiffness (STF_max and STF_80%) and viscoelasticity (stress-relaxation test (SRT)). Results: A significant interaction between time and intervention was found for knee ROM (p = 0.017), PRT (p = 0.044), and STF_max (p = 0.042). NDNG induced an increase in ROM (p = 0.011), PRT (p = 0.008), and STF_max (p = 0.030). Both NDNG and FR induced an increase in SLR (p < 0.001). No interaction or main effects was found for SRT and AKJPS. Conclusion: The inclusion of NDNG in the warm-up routine increased the ROM more in comparison with FR and may be of benefit to soccer players.

Adolescent athletes are particularly vulnerable to stress. The current study aimed to monitor one of the most popular and accessible stress markers, heart rate variability (HRV), and its associations with training load and sleep duration in young swimmers during an 11-week training period to evaluate its relevance as a tool for monitoring overtraining. National-level swimmers (n = 22, age 14.3 ± 1.0 years) of sprint and middle distance events followed individually structured training programs prescribed by their swimming coach with the main intention of preparing for the national championships. HRV after awakening, during sleep and training were recorded daily. There was a consistent ~4.5% reduction in HRV after 3–5 consecutive days of high (>6 km/day) swimming volume, and an inverse relationship of HRV with large (>7.0 km/day) shifts in total training load (r = −0.35, p < 0.05). Day-to-day HRV did not significantly correlate with training volume or sleep duration. Taken together, these findings suggest that the value of HRV fluctuations in estimating the balance between the magnitude of a young athlete’s physical load and their tolerance is limited on a day-to-day basis, while under sharply increased or extended training load the lower HRV becomes an important indicator of potential overtraining.