Influence of physical qualities on post-match fatigue in rugby league players

Abstract

Objectives

This study examined the influence of physical qualities on markers of fatigue and muscle damage following rugby league match-play.

Design

Between subjects design.

Methods

Twenty-one male youth rugby league players (age 19.2 ± 0.7 years; height 180.7 ± 5.6 cm; body mass 89.9 ± 10.0 kg) participated in the study. Yo-Yo intermittent recovery test (level 1), 3 repetition maximum back squat and bench press were assessed prior to 2 competitive fixtures. Neuromuscular fatigue (countermovement jump [CMJ] and plyometric push-up [PP]), and blood creatine kinase (CK) were assessed before and after match-play. During match-play, movements were recorded using microtechnology. Players were divided into high- and low-groups based on physical qualities.

Results

High Yo-Yo and squat performance resulted in greater loads during match-play (p < 0.05). There were larger reductions in CMJ power in the low Yo-Yo group at both 24 (ES = −1.83), and 48 h post-match (ES = −1.33). Despite greater internal and external match loads, changes in CMJ power were similar between squat groups. There were larger increases in blood CK in the low Yo-Yo group at 24 (73% vs. 176%; ES = 1.50) and 48 h post-match (28% vs. 80%; ES = 1.22). Despite greater contact loads, the high squat group exhibited smaller changes in blood CK post-match (ES = 0.25–0.39).

Conclusions

Post-match fatigue is lower in players with well-developed high-intensity running ability, and lower body strength, despite these players having greater internal and external match loads.

Introduction

Rugby league is an intermittent team sport where players repeatedly perform bouts of high-speed running and physical collisions interspersed with periods of low-speed activity.¹ These demands result in increased markers of muscle damage, neuromuscular and perceptual fatigue.2, 3 While generally transient in nature, this fatigue typically persists for 24–48 h after competition, although muscle damage may last for several days.³ High levels of residual fatigue and markers of muscle damage have the potential to compromise performance through reductions in low- and high-speed movements, as well as tackling proficiency.4, 5

Understanding and managing the fatigue response to match-play may allow optimal preparation for subsequent performance. While various interventions are often employed to facilitate recovery following match-play, their efficacy is often questioned.6, 7 Currently, it is unclear whether any intrinsic qualities influence the fatigue response observed following competition. Findings from Australian rules football found that across a season, players with higher 6 min run performance showed smaller disturbances in blood creatine kinase (CK) prior to competition.⁸ In addition, well-developed physical qualities reduce transient fatigue following physical exertion. In particular, greater aerobic fitness results in smaller decrements in repeated-sprint performance.9, 10 Fitter athletes may experience smaller metabolic disturbances following high-intensity activity, resulting in less acute fatigue.¹¹ These data suggest that aerobic fitness could reduce residual fatigue and muscle damage following competition.

In addition to aerobic fitness, muscular strength has the potential to influence the fatigue response. Although collisions play a major role in the muscle damage and fatigue response,2, 12 high-speed movements also induce symptoms of fatigue.2, 5, 12 Therefore, players who possess greater muscular strength and eccentric strength in particular, may be more suited to dealing with the forces associated with these movements. Indeed, greater strength appears to augment the stretch-shortening cycle, potentially placing less stress on the contractile components of the muscle.13, 14 Byrne et al.¹⁵ suggested that enhancing the stretch-shortening cycle capabilities of the muscle may moderate the effects of muscle damage. Therefore, greater muscular strength may limit neuromuscular fatigue and muscle damage following match-play.

The purpose of this study is to assess whether physical qualities influence post-match markers of fatigue in rugby league players. Such information would allow coaches to better manage post-game recovery practices and reduce disruption to training. It is hypothesised that greater high-speed running ability and muscular strength will be associated with reductions in post-game neuromuscular fatigue and markers of muscle damage.