Impact Control in High-Intensity Interval Training Can Be Improved by Creatine Supplementation

Abstract

High-intensity interval training (HIIT) is an exercise mode designed to repeatedly stress the body with intense stimulus. Intense running can increase impact forces and alter muscle activation intensity. As skeletal muscles have an important role in shock attenuation, the depletion of muscle phosphorylcreatine (PCr) stores and the diminished energy sources could lead to exhaustion and impairments in the protective functions of muscle during running. We hypothesize creatine supplementation could avoid peripheral fatigue during intense exercise and reduce impairments on shock attenuation. PURPOSE: This study investigated the effects of creatine supplementation on biomechanical parameters related to shock attenuation during a session of HIIT. METHODS: A single-blind, placebo-controlled, crossover design was adopted to test 8 elite soccer players (males; 16.3± 0.5 years; 70.7 ± 4.16 kg; 1.78± 0.06 m) during HITT sessions under two conditions: after placebo supplementation (Pl) and after creatine supplementation (Cr). HITT test sessions consisted of an intermittent test (5 bouts of running) with constant load applied until exhaustion was reached. The vertical component of Ground Reaction Force (VGRF) and Electromyography (EMG) data were recorded by Gaitway and Lynx-EMG Systems, respectively. Heart rate (HR), Rated Perceived Exertion (RPE – Borg’s Scale) and lactate concentration were also obtained. RESULTS: Creatine supplementation did not affect HR, RPE and lactate concentration. Decreased values (p<0.05) of magnitude of first peak (Fy1) of VGRF and impulse of first 50 ms (Imp50) were observed for Cr (about 16.2 – 24.2% and 34.3% of decrease, respectively), whereas higher values (p<0.05) of time to reach first peak (tFy1) were detected for Cr as compared to Pl (28.9 % of increase). Significant modifications (p<0.05) in muscle activation were also observed. Changes occurred in intermediary bouts, mainly in bout 2. CONCLUSION: Creatine supplementation has potential to influence biomechanical parameters related to impact control during a single session of HIIT based on running. Results indicate possible improvements in shock attenuation under creatine supplementation.