Abstract
BackgroundThe current study examined the acute effects of a lower body resistance training (RT) session on physiological and thermoregulatory measures during a sub-maximal running protocol in the heat in heat-acclimatized men. Ten resistance-untrained men (age 27.4 ± 4.1 years; height 1.78 ± 0.06 m; body mass 76.8 ± 9.9 kg; peak oxygen uptake 48.2 ± 7.0 mL kg−1 min−1) undertook a high-intensity RT session at six-repetition maximum. Indirect muscle damage markers (i.e., creatine kinase [CK], delayed-onset muscle soreness [DOMS], and countermovement jump [CMJ]) were collected prior to, immediately post and 24 and 48 h after the RT session. The sub-maximal running protocol was performed at 70% of the ventilatory threshold, which was conducted prior to and 24 and 48 h following the RT session to obtain physiological and thermoregulatory measures.ResultsThe RT session exhibited significant increases in DOMS (p < 0.05; effect size [ES]: 1.41–10.53), whilst reduced CMJ (p < 0.05; ES: − 0.79–1.41) for 48 h post-exercise. There were no differences in CK (p > 0.05), although increased with moderate to large ES (0.71–1.12) for 48 h post-exercise. The physiological cost of running was increased for up to 48 h post-exercise (p < 0.05) with moderate to large ES (0.50–0.84), although no differences were shown in thermoregulatory measures (p > 0.05) with small ES (0.33).ConclusionThese results demonstrate that a RT session impairs sub-maximal running performance for several days post-exercise, although thermoregulatory measures are unperturbed despite elevated muscle damage indicators in heat-acclimatized, resistance untrained men. Accordingly, whilst a RT session may not increase susceptibility to heat-related injuries in heat-acclimatized men during sub-maximal running in the heat, endurance sessions should be undertaken with caution for at least 48 h post-exercise following the initial RT session in resistance untrained men.
Highlights
The current study examined the acute effects of a lower body resistance training (RT) session on physiological and thermoregulatory measures during a sub-maximal running protocol in the heat in heat-acclimatized men
The changes in body mass were significantly greater at tests were performed 24 (T24) (− 1.24 ± 0.38 kg; p = 0.03; Effect size (ES) = 0.60) and 48 h post-exercise (T48) (− 1.34 ± 0.36 kg; p = 0.01; ES = 0.76) when compared to Baseline time point (TBase) (− 1.08 ± 0.30 kg)
No changes were found in the thermal measures of Core temperature (TC) at T24 (p = 0.552), DT or ST at T24 (p = 0.53 and p = 1.00, respectively) and T48 (p = 0.08 and p = 0.50, respectively) with small ES (0.11–0.46; Table 2)
Summary
The current study examined the acute effects of a lower body resistance training (RT) session on physiological and thermoregulatory measures during a sub-maximal running protocol in the heat in heat-acclimatized men. Exercise-induced muscle damage (EIMD) impairs running economy (RE) measures by elevating oxygen cost of running at sub-maximal intensities [1, 2] Whilst these findings may have implications for the quality of running session during periods of EIMD [3, 4], the majority of studies examining the impact of EIMD on determinants of running performance have incorporated isokinetic, eccentric contractions [5, 6] or downhill running protocols [1, 7]. Studies have reported that lower body RT sessions, such as squats, leg press, leg extension and leg curls, produced symptoms of EIMD [8], and as a result, impaired RE measures and maximal effort running performance for 24–48 h post-exercise [9,10,11] These studies examined running performance measures in thermo-neutral conditions. As athletes experience greater thermal strain in hot and humid conditions [12, 13], and the symptoms of EIMD increases physiological cost during exercise at a given workload [11, 14], running during periods of EIMD in the heat may further augment thermal strain
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