This study aimed to compare force, velocity, and power output collected under different loads, as well as the force-velocity (F-V) relationship between three measurement methods. Thirteen male judokas were tested under four loading conditions (20, 40, 60, and 80 kg) in the countermovement jump (CMJ) exercise, while mechanical output data were collected by three measurement methods: the Samozino's method (SAM), a force platform (FP), and a linear velocity transducer (LVT). The variables of the linear F-V relationship (maximum force [F0], maximum velocity [V0], F-V slope, and maximum power [P0]) were determined. The results revealed that (1) the LVT overestimated the mechanical output as compared to the SAM and FP methods, especially under light loading conditions, (2) the SAM provided the lowest magnitude for all mechanical output, (3) the F-V relationships were highly linear either for the SAM (r = 0.99), FP (r = 0.97), and LVT (r = 0.96) methods, (4) the F-V slope obtained by the LVT differed with respect to the other methods due to a larger V0 (5.28 ± 1.48 m·s-1) compared to the SAM (2.98 ± 0.64 m·s-1) and FP (3.06 ± 0.42 m·s-1), and (5) the methods were significantly correlated for F0 and P0, but not for V0 or F-V slope. These results only support the accuracy of the SAM and FP to determine the F-V relationship during the CMJ exercise. The very large correlations of the SAM and LVT methods with respect to the FP (presumed gold-standard) for the mean values of force, velocity and power support their concurrent validity for the assessment of mechanical output under individual loads.

This study examined the acute effects of exposure to moderate altitude on factors associated with muscular adaptations following whole‐body hypertrophy‐oriented resistance training (R _T) sessions. Thirteen resistance‐trained males completed both counterbalanced standard hypertrophic R _T sessions (3 sets × 10RM, 2 min rest) at moderate‐altitude (H; 2320 m asl) and under normoxic conditions (N; <700 m asl). Participants rested 72 h between training sessions. Before and after the exercise session, blood samples were obtained for determination of metabolites and ions (lactate, inorganic phosphate, liquid carbon dioxide and calcium) and hormones (testosterone and growth hormone). Session‐related performance and perception of effort (s‐RPE) were also monitored. Results showed no meaningful differences in performance or s‐RPE (8.5 ± 1.4 vs 8.6 ± 0.8 respectively for N and H; p = 0.603). All blood variables displayed statistically significant changes throughout the recovery period compared to basal levels (p < 0.05), except for the testosterone. However, no altitude effect was observed in maximal blood lactate, calcium or anabolic hormones (p > 0.05). The reduction observed in the liquid carbon dioxide concentration in H (21.11 ± 1.46 vs 16.19 ± 1.61 mmol·l⁻¹) seems compatible with an increase in buffering capacity. Compared to N, inorganic phosphate displayed lower recovery values after the R _T in H (2.89 ± 0.64 vs 2.23 ± 0.60 mg dl⁻¹; p = 0.007). The results of this study do not support an accentuated effect of acute moderate terrestrial hypoxia on metabolic and hormonal factors linked to muscle growth during hypertrophic resistance training.

Hypobaric hypoxia (HH) seems to lead to different responses compared to normobaric hypoxia (NH) during physical conditioning. The aim of the study was to analyze the hormonal and circulating ion responses after performing high-intensity resistance training with different inter-set rest under HH and NH condition. Sixteen male volunteers were randomly divided into two training groups. Each group completed two counterbalanced resistance training sessions (three sets × ten repetitions, remaining two repetitions in reserve), with both one- and two-minute inter-set rest, under HH and NH. Blood samples were obtained to determine hormones and circulating ions (Ca²⁺, Pi, and HCO₃⁻) at baseline and after training sessions (5, 10, and 30 min). Resistance training with one-minute rest caused greater hormonal stress than with two-minute rest in cortisol and growth hormone, although the hypoxic environmental condition did not cause any significant alterations in these hormones. The short inter-set rest also caused greater alterations in HCO₃⁻ and Pi than the longer rest. Additionally, higher levels of Ca²⁺ and Pi, and lower levels of HCO₃⁻, were observed after training in HH compared to NH. Metabolic and physiological responses after resistance training are mediated by inter-set rest intervals and hypoxic environmental condition. According to the alterations observed in the circulating ions, HH could cause greater muscular fatigue and metabolic stress than NH.

This study investigated the effects of a 3‐week power‐oriented resistance training programme performed at moderate altitude on the lower‐limb maximal theoretical power and force‐velocity (F‐V) imbalance of elite judokas. Twenty‐two elite male judokas were randomly assigned to either a hypobaric hypoxia or normoxia group. Mechanical outputs from an incremental loaded countermovement jump test were assessed at sea level, before and after training, and 1 week later. Results indicated an increase in the maximal theoretical force and a reduction in the F‐V imbalance both at moderate altitude and sea level. Altitude training induced additional benefits when compared to sea level for F‐V imbalance (8.4%; CI: 0.3, 17.3%), maximal theoretical power (2.09 W·kg⁻¹; CI: 0.13, 4.52 W·kg⁻¹) and force (1.32 N·kg⁻¹; CI: −0.12, 2.96 N·kg⁻¹), jump height (3.24 cm; CI: 2.02, 4.80 cm) and optimal maximal theoretical force (1.61 N·kg⁻¹; CI: 0.06, 3.60 N·kg⁻¹) and velocity (0.08 m·s⁻¹; CI: 0.00, 0.17 m·s⁻¹) after the training period. The hypoxia group achieved their best results immediately after the training period, while the normoxia group achieved them one week later. These results suggest that a power‐oriented resistance training programme carried out at moderate altitude accelerates and improves the gains in lower‐limb muscle power, while minimizing lower‐limb imbalances. Therefore, it seems appropriate to compete immediately after the return to sea level and/or use altitude training as a tool to improve muscle power levels of athletes without tapering goals, especially in highly trained power athletes, since their window of adaptation for further power enhancement is smaller.

In competition, swimmers alternate between swimming on the surface and underwater; they therefore train in apnea to improve their tolerance to lack of oxygen during exercise, even though research in this area remains limited. The aim of the study was to investigate the impact of underwater swimming on physiological and perceptual responses of competitive swimmers. Eighteen national level swimmers (700.25 ± 53.42 AQUA points) performed 6 × 25m maximal swimming efforts from a push start with 3 minutes rest in three different conditions: underwater (without breathing), surface (with normal breathing pattern) and competitive (composed of an underwater plus a surface swimming segment) swimming. Swimming performance (T25), gases exchange, heart rate (HR), arterial oxygen saturation (SpO ₂ ), blood parameters, rating of perceived exertion (RPE) and subjective feeling (FS) were measured. The underwater condition produced a greater increase in blood lactate (Lac) ( p < 0.05; η2 = 0.67) and potassium ( p < 0.05; η2 = 0.35) than the surface and competitive conditions. No significant differences ( p > 0.05) were observed in HR, SpO ₂ or RPE, whereas FS values were lower (more unpleasant) in the underwater swimming condition. However, oxygen uptake (VO ₂ ) was significantly lower ( p < 0.003; η2 = 0.09) ) in underwater than in competitive swimming. This study shows that a set of 25m underwater swimming efforts at maximum intensity generates an intense muscular, perceptive and metabolic demand in competitive swimmers, well tolerated by young trained competitive swimmers.