Comparing the Acute Effects of a Session of Isometric Strength Training with Heavy Resistance Training on Neuromuscular Function

Purpose This study compared the acute effects of a session of isometric strength training (ISO) with heavy resistance training (HRT) training on 20-m sprint, countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) performance.Methods Ten resistance-trained athletes (age: 26.7 +/- 6.2 years, body mass: 71.5 +/- 16.2 kg, height: 1.68 +/- 0.10 m) performed baseline measures for 20-m sprint, CMJ and IMTP prior to either an ISO or HRT session. During both training sessions, participants performed back squats, Romanian deadlift and split squat. Post-test performances were measured 5 min and 24 h after each training session. Participants returned a week later to perform the other training session.Results A significant time x condition effect was found for 20-m sprint time (P = 0.007) and IMTP peak force (P = 0.003). Main time effect was observed for 20-m sprint (P < 0.001), CMJ height (P < 0.001) and IMTP peak force (P < 0.001). HRT resulted in a greater increase in sprint time at 5 min (0.17 +/- 0.12 vs. 0.06 +/- 0.05 s, P = 0.013, g = 1.15) and 24 h (0.01 +/- 0.09 vs. 0.00 +/- 0.05 s, P = 0.004, g = 1.32) post-training as compared to ISO. Similarly, HRT resulted in a significantly larger reduction in IMTP peak force than ISO at both 5 min (- 363.3 +/- 248.8 vs. - 98.9 +/- 230.3 N, P = 0.024, g = 1.06) and 24 h (- 289.2 +/- 256.2 vs. 37.9 +/- 177.8 N, P = 0.004, g = 1.42) post-training. Total impulses generated during each exercise were greater during ISO than HRT (P < 0.001-0.006). Rating of perceived recovery post 24 h was higher in ISO than HRT (P = 0.002).Conclusion The above results indicated that acute HRT led to a greater reduction in sprinting strength performance and lower perceived recovery post-24 h than ISO.