Background: Water jumping exercise is an alternative method to achieve maintenance of bone health and reduce exercise injuries. Clarifying the ground reaction force (GRF) of moderate and high cardiopulmonary exercise intensities for jumping movements can help quantify the impact force during different exercise intensities. Accelerometers have been explored for measuring skeletal mechanical loading by estimating the GRFs. Predictive regression equations for GRF using ACC on land have already been developed and performed outside laboratory settings, whereas a predictive regression equation for GRF in water exercises is not yet established. The purpose of this study was to determine the best accelerometer wear-position for three exercise intensities and develop and validate the ground reaction force (GRF) prediction equation. Methods: Twelve healthy women (23.6 ± 1.83 years, 158.2 ± 5.33 cm, 53.1 ± 7.50 kg) were recruited as participants. Triaxial accelerometers were affixed 3 cm above the medial malleolus of the tibia, fifth lumbar vertebra, and seventh cervical vertebra (C7). The countermovement jump (CMJ) cadence started at 80 beats/min and increased by 5 beats per 20 s to reach 50%, 65%, and 80% heart rate reserves, and then participants jumped five more times. One-way repeated analysis of variance was used to determine acceleration differences among wear-positions and exercise intensities. Pearson’s correlation was used to determine the correlation between the acceleration and GRF per body weight on land (GRF_VL_BW). Backward regression analysis was used to generate GRF_VL_BW prediction equations from full models with C7 acceleration (C7 ACC), age, percentage of water deep divided by body height (PWDH), and bodyweight as predictors. Paired t-test was used to determine GRF_VL_BW differences between values from the prediction equation and force plate measurement during validation. Lin’s CCC and Bland–Altman plots were used to determine the agreement between the predicted and force plate-measured GRF_VL_BW. Results: The raw full profile data for the resultant acceleration showed that the acceleration curve of C7 was similar to that of GRFv. The predicted formula was − 1.712 + 0.658 * C7ACC + 0.016 * PWDH + 0.008 * age + 0.003*weight. Lin’s CCC score was 0.7453, with bias of 0.369%. Conclusion: The resultant acceleration measured at C7 was identified as the valid estimated GRF_VL_BW during CMJ in water.

Muscle strength after detraining is still higher than the level before training, which is an important issue for middle-aged and older adults. The purpose of the present study was to examine the effects of detraining duration (DD), resistance training duration (RTD), and intensity on the maintenance of resistance training (RT) benefits after detraining in middle-aged and older adults. A systematic search yielded 15 randomized control trails (n = 383) eligible for inclusion. The results showed that RTD ≥ 24 weeks and DD ≥ RTD, the RT benefits were still significantly maintained even with medium and low intensity (standardized mean difference = 1.16, 95% confidence interval, CI [0.38, 1.94], p = .004). When RTD < 24 weeks and DD ≤ RTD, only the high-intensity groups maintained the RT benefits (DD, 4–6 weeks: standardized mean difference = 0.71, 95% CI [0.34, 1.08], p = .0002; DD 8–16 weeks: standardized mean difference = 1.35, 95% CI [0.66, 2.04], p = .0001). However, when DD > RTD, the RT benefits were not maintained even with high intensity. In summary, when RTD was less than 24 weeks, RTD > DD was an important factor in maintaining muscle strength.

β-alanine is a well-established ergogenic aid that enhances muscle carnosine levels and buffering capacity during high-intensity efforts. However, its role in improving strength and power performance remains inconsistent across the literature. This systematic review investigates whether dosing strategy, rather than duration alone, is the critical determinant of efficacy in resistance-trained populations. A systematic search was conducted across PubMed, SPORTDiscus, Scopus, Web of Science, and Google Scholar up to 28 May 2025, following PRISMA guidelines. Studies were included based on the PICO framework, targeting trained individuals receiving β-alanine supplementation with defined dosing protocols and strength- or power-based outcomes. Methodological quality was assessed using the Joanna Briggs Institute tools. Nine studies comprising 197 participants were reviewed. Daily β-alanine doses between 4 g and 6.4 g, especially when divided into multiple smaller servings such as 0.8 g taken several times a day, were more likely to enhance maximal strength and power-related outcomes. In contrast, studies that used high total doses but relied on sustained-release formats, single large servings, or training protocols with limited metabolic stress such as low volume or long rest intervals often failed to show improvements in performance. These findings suggest that cumulative dose and delivery method may play a more critical role than duration alone in promoting strength and power adaptations. To optimize strength and power outcomes, β-alanine supplementation should emphasize fragmented dosing protocols of 4-6.4 g/day sustained over 5-8 weeks, particularly when implemented during training phases characterized by high metabolic stress - such as repeated submaximal efforts, short rest intervals, or high-volume hypertrophy sessions that elevate intramuscular acidity. These findings offer refined guidelines for coaches, athletes, and sport nutrition practitioners, and highlight the need for more individualized and mechanistically informed supplementation strategies.

BACKGROUND: This study aimed to investigate the effects of cold water immersion (CWI) recovery strategies on the blood pressure levels and related physiological parameters after high-intensity intermittent exercise (HIIE). METHODS: This randomized crossover study included 20 men (21.5 +/- 1.6 years). Each participant performed a maximum-exertion exercise performance test on a bicycle, and heart rate was measured. Subsequently, six cycles of HIIE (1 minute at 120% heart rate reserve [HRR] and 4 minutes at 40% HRR) were performed in a random sequence, and the recovery period involved either CWI or static rest (SR). RESULTS: Systolic and diastolic blood pressure levels at the 6th and 20th minute of CWI recovery were significantly higher than those during SR and significantly higher than those during a quiet state at the 6th minute. The heart rates at the 20th minute and 35th minute of CWI recovery were significantly lower than that during SR, and the ratings of perceived exertion (RPE) at the 6th and 20th minute of CWI recovery were significantly lower than that during SR. No significant difference in lactate production was evident between the two recovery strategies. Ear temperature was not significantly different when it was quiet, at the end of exercise, and at the 6th and 35th minute of recovery; however, at the 20th minute of recovery, ear temperature during CWI was significantly higher than that during SR. CONCLUSIONS: CWI after HIIE reduced the extent to which blood pressure decreased. For the fatigue-related heart rate and RPE indicators, CWI was superior to SR.