Abstract
The purpose of this study was to compare the variations of weekly workload indices of internal and external load measures across the three weeks prior to injury occurrences in trail runners. Twenty-five trail runners (age: 36.23 ± 8.30 years old; body mass: 67.24 ± 5.97 kg; height: 172.12 ± 5.12 cm) were monitored daily for 52 weeks using global positioning systems (GPSs) to determine the total distance covered. Additionally, a rate of perceived exertion (RPE) scale was applied to determine session-RPE (sRPE: RPE multiplied by training time). The accumulated load (AL), acute: chronic workload ratio (ACWR), training monotony (TM), and training strain (TS) indices were calculated weekly for each runner. During the period of analysis, the injury occurrences were recorded. The differences were observed in AL and ACWR for sRPE and training time were significantly greater during the injury week when compared to the previous weeks. Similar evidence was found in TM and TS indices for sRPE, training time, and total distance. Furthermore, no meaningful differences were observed in AL and ACWR for total distance in the weeks prior to injury occurrence. Nevertheless, significant between-subjects variability was found, and this should be carefully considered. For that reason, an individualized analysis of the workload dynamics is recommended, avoiding greater spikes in load by aiming to keep a progressive increment of load without consequences for injury risk.
Highlights
Training is defined as the process by which athletes improve their skills through various exercises resulting from the training process [1]
The results in this study revealed that the acute: chronic workload ratios for sRPE, total distance, and training time remained between 0.7 and 1.3, it is necessary to analyze the data carefully, as the standard deviations are very similar to the mean values, revealing a very high coefficient of variation and suggesting high variation within subjects [58], which is especially evident in week-3 for all external and internal measures
The variations in the weekly load demonstrate a drop in the workloads for the external and internal measures from week-3 to week-2, which was followed by increases from week-2 until the injury week
Summary
Training is defined as the process by which athletes improve their skills through various exercises resulting from the training process [1]. Considering the cause–effect relationship between training and stimuli [3], monitoring the load and the athlete is one of the important mechanisms that can help coaches to maximize the positive effects of overload without exposing players to an increase in injury risk. Overload is part of the training process to enhance adaptations on athletes, the stimuli–recovery must be considered while identification of possible risk factors (i.e., mediators of injury associated to greater spikes in load) should be tracked [4]. It is a complex process, combining external factors (related to the task) and internal factors (related to the athlete), which are differentiated for each sport [4,5].
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