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Research has shown a moderate-strong relationship between training load and injury; (1) higher chronic loads have been associated with lower injury risk, while (2) injury risk significantly increases with rapid increases (i.e. spikes) in training load.¹ Injury reduction is an important pursuit for high performance teams as greater availability has been directly linked with better performances.^2-4 Given that no trophies are given for the least number of injuries sustained during a season, it is reasonable to question if the strong relationship between training load and injury also applies for training load and performance.

Training Load and Performance in Self-Paced Individual Sports

Several studies have investigated the influence of training load on athletic performance, with performance generally improving with increases in training load.^5-6 For example, in an early study of cyclists, runners, and speed skaters, a 10-fold increase in training load was associated with a ~10% improvement in performance.⁵ Furthermore, others have reported a significant positive relationship between greater training volume and performance (r=0.50-0.80) and greater training intensity and performance (r=0.60-0.70) in competitive swimmers.⁶ Although several factors can impact performance, these results demonstrate that in self-paced, individual sports, the applied training load contributes significantly to overall performance. But what about team sport performance?

Training Load and Performance in Team Sport Athletes

In a recent systematic review, Fox et al.⁷ investigated the relationship between training load and performance outcomes in team sport athletes. The key findings from this review included:

• Greater training exposure was associated with better aerobic performance;
• A greater proportion of time spent at high intensities (>90% maximum heart rate) was associated with better aerobic performance;
• No clear associations were found between training load and neuromuscular variables or game-related statistics.

Given these findings, a simplistic view may be that in team sports (1) training load only improves aerobic performance, (2) when that training is of sufficiently high-intensity, but (3) training load has no effect on in-game performance. However, it is important to note that at the time of the review, the vast majority of research had used internal rather than external training load measures (10 vs. 5 studies), measured aerobic (10 studies) rather than neuromuscular (1 study) variables, with performance outcomes predominantly measured via physiological assessments (16 studies) rather than in-game performance (2 studies). It is difficult to find associations between variables when those variables have not been measured in previous studies!

What Does the Latest Research Tell Us About Training Load and Performance in Team Sport Athletes?

High-intensity intermittent team sports (such as soccer, basketball, lacrosse, and ice hockey) require players to perform high-intensity actions (e.g. running, jumping, or skating) interspersed with short recovery periods. Although prolonged high-intensity effort ability is critical for these sports, it is difficult and often impractical to assess these qualities in-season, when players are recovering from game-to-game. Recently, Hulin et al.⁸ addressed this issue in professional team sport athletes. They demonstrated a relationship between a maximal-effort running test and sub-maximal running performance; players with better maximal-effort running ability also had the best heart rate recovery following a 4-minute sub-maximal running test. These findings demonstrate the utility of a sub-maximal test to infer maximal-effort ability in team sport athletes and demonstrate that a sub-maximal test may be appropriate to use when maximal-effort testing is impractical. In a subsequent study, these authors investigated the relationship between training load, injury and performance.⁹ There were 3 key findings from this study that are directly applicable to high performance practitioners:

• Lower chronic loads and higher acute:chronic workload ratios were associated with poorer sub-maximal running test performance (Figure 1);
• Poorer sub-maximal running test performance was associated with greater injury risk (consistent with several other studies, rapid spikes in training load were also associated with greater injury risk);
• In contrast to the common belief that exponentially weighted moving averages (EWMA) offer the best approach to modelling the acute:chronic workload ratio, no differences were found between EWMA and rolling averages in terms of the training-performance relationship.