Exploring the presence of mental fatigue in elite orienteering training and competition

Abstract

Laboratory-based experiments have found that engaging in mentally demanding tasks can induce mental fatigue (MF), which is known to impair endurance and decision-making performance in sports. However, these experiments often lack ecological validity, and their generalisability is limited by individual differences in the perception of MF. These differences can be influenced by factors such as training level, environment, and occupation. Consequently, the transferability of findings from laboratory-based intervention to real-world sports settings may be limited. To address these limitations and improve our understanding of MF in applied sports contexts, this thesis explores how orienteers perceive and respond to MF in ecologically valid environments. This thesis comprises three studies investigating the presence and impact of MF in orienteering.

Study 1 employed a three-round online Delphi approach with 24 international orienteering athletes and practitioners to explore sport-specific perspectives on MF. The consensus reached in this study showed that international orienteering experts recognise the occurrence of MF during both orienteering training and competition, while also reinforcing differences in how MF is perceived between these contexts. However, there was no consensus that MF experienced in competition could be replicated in orienteering training. Furthermore, no consensus was reached on the existing definition of MF accurately reflects the MF experienced in orienteering. Consequently, a sport-specific definition of MF was developed to increase specificity and clarity in future research and support more accurate discussions of MF within the context of orienteering.

Study 2 analysed 43 orienteering races from 16 national-level orienteers and found a moderate increase in perceived MF (ES = 0.84 [0.49 , 1.19], mean difference: 19.7 [12.5 , 27.2]) following an orienteering competition. The increased MF ratings sustained up to 48 hours, with the perceived MF ratings remaining higher than pre-competition values to a small extent (ES = 0.54 [0.08 to 1.15], mean difference: 10.4 [-1.8 , 22.7]). These findings imply that orienteering competition can acutely induce perceived MF, with effects that may extend beyond the immediate post-competition period and influence recovery.

Study 3 examined the changes in perceived MF and other psychological responses among eleven national junior orienteers during a 4-day orienteering training camp. The combined analysis of 42 pre- and post-orienteering training responses found a moderate increase in perceived MF (ES = 1.06 [0.66 , 1.45], mean difference: 22.5 [15.6 , 29.5]). A moderate increase in perceived MF was observed following each training session, with a cumulative effect resulting in the highest MF ratings on the final day of the training camp. Importantly, perceived MF remained moderately elevated 48 hours after the termination of the orienteering training camp compared to the initial pre-camp ratings (ES = 0.86 [-0.07 , 1.75], mean difference 17.3 [-1.7 , 36.3]), suggesting that simulated orienteering training can also induce sustained MF.

Importantly, studies 2 and 3 revealed significant individual variability in perceived MF and related psychological responses such as physical fatigue, stress, tiredness, and mood states. These findings highlight that orienteers experience MF differently. The model comparison consistently supported the use of random intercept models that accounted for individual variability, emphasising the importance of considering variability between participants in statistical analyses. Furthermore, the differences in the magnitude and pattern of changes across outcome variables support the interpretation that MF is a different fatigue construct. Therefore, MF should be monitored and managed separately from other psychological responses.

In summary, this thesis provides evidence that both national and junior national-level orienteers experience MF during orienteering training and competition. This thesis advances the conceptual understanding of MF in orienteering by providing an orienteering-specific definition of MF and reinforces the importance of ecologically valid research designs that reflect the real-world experiences of athletes. Future research should investigate the acute and cumulative impact of MF on orienteering performance and recovery, as well as develop individualised strategies to monitor and manage MF alongside other psychological responses. This will be essential for optimising performance, recovery and fatigue management in orienteering.