Background: Warm-up strategies are essential for optimizing strength-training performance. Traditional warm-ups improve neuromuscular readiness, whereas post-activation potentiation (PAP) has been proposed to acutely enhance muscular output. This randomized crossover study compared the acute effects of traditional and PAP-based warm-ups on local muscular endurance (LME) during free weight back squats in resistance-trained men. Methods: Twelve trained males (age: 41.3 ± 5.7 years; one repetition maximum squat: 129.3 ± 14.3 kg) completed three randomized squat sessions: mobility with LME (M + LME), traditional warm-up with LME (T + LME), and PAP with LME (PAP + LME). The sessions were spaced 48 h apart. Outcomes included the number of repetitions, blood lactate concentration, time under tension (TUT), perceived exertion through OMNI Resistance Exercise Scale (OMNI-RES), and pain perception through visual analogue scale (VAS). One-way ANOVA and partial eta-squared (η²p) were used for statistical analyses. Results: PAP + LME significantly increased the number of repetitions (15.63 ± 3.66) compared to both M + LME (12.38 ± 3.89) and T + LME (13.63 ± 3.82; p < 0.0001). Blood lactate levels were significantly higher in PAP + LME (8.98 ± 3.87 mmol/L) compared to M + LME (5.08 ± 0.97 mmol/L; p = 0.01). TUT was significantly shorter in both the PAP + LME and T + LME groups than in the M + LME group (p < 0.05). VAS scores were higher after PAP + LME (8.50 ± 0.45) than after M + LME (6.50 ± 1.20; p = 0.02), while OMNI-RES scores did not differ significantly between the protocols. Conclusions: Both traditional and PAP-based warm-ups improved squat LME compared with mobility alone. PAP elicited greater repetition performance and metabolic stress but also increased discomfort. Warm-up selection should align with training goals, balancing performance benefits and perceived fatigue.

Background: This study compared energy expenditure (EE), substrate metabolism, and excess post-exercise oxygen consumption (EPOC) during moderate-intensity continuous training (MICT), high-intensity interval training (HIIT), and high-intensity circuit training (HICT) isocaloric sessions. Methods: Twelve trained male participants completed isocaloric exercise sessions equalized for EE and average power (AP) across the three modalities. Postexercise EE, carbohydrate and lipid oxidation rates, and EPOC were measured 30 and 60 min after training. Results: Total EE and AP during exercise were similar between the protocols. However, EPOC was significantly higher for HIIT (319.0 ± 88.03 mL) and HICT (329.1 ± 27.79 mL) than for MICT (168.5 ± 21.84 mL), demonstrating greater post-exercise metabolic demand in high-intensity protocols. At 30 min post-exercise, carbohydrate oxidation remained elevated in the HIIT (3.70 ± 1.04 mg/kg/min) and HICT (4.06 ± 1.03 mg/kg/min) groups compared to that in the MICT group (1.42 ± 0.58 mg/kg/min), while lipid oxidation rates were also higher (HIIT: 1.08 ± 0.41; HICT: 1.20 ± 0.24 mg/kg/min; MICT: 0.61 ± 0.20 mg/kg/min). These effects persisted for 60 min, with HIIT and HICT maintaining significantly greater carbohydrate and lipid oxidation than MICT. Correlation analysis indicated a strong relationship between carbohydrate oxidation during exercise and lipid oxidation after 60 min of exercise. Conclusions: High-intensity protocols (HIIT and HICT) promote prolonged postexercise EE, enhance carbohydrate and lipid oxidation, and optimize metabolic recovery, making them effective strategies for maximizing energy utilization beyond the training session.

The main of the present study was to identify the heart rate threshold based on heart rate kinetics during graded maximal exercise in football players. Twenty-six male football players performed a maximal exercise test (Bruce protocol) on a motor-driven treadmill. Oxygen uptake (VO₂) and heart rate (HR) were monitored, recorded and resampled at 3.5Hz. The ventilatory threshold (VT), and respiratory compensation (RC), heart rate deflection points (HRDP1 and HRDP2) and heart rate kinetics threshold (HRT) were determined by computerized methods. The heart rate variability (HRV) was assessed in the frequency domain. The HRT averaged 89.9 ± 1.2 % of the VO₂ peak. The HRT showed poor correlations and significant differences compared with HRDP1 (r = 0.46) and VT (r = 0.51), but was not different from, and highly correlated with, HRDP2 (0.98) and RC (0.90). Bland Altman plots showed all athletes into 95% of limits of agreement, and intraclass correlation coefficient showed good agreements between points obtained from HRT compared with HRDP2 (0.96) and RC (0.98). The HRT was highly correlated with HRDP2 and RC, suggesting it could be a marker for cardiorespiratory fatigue.