Reducing Muscular Fatigue in Trail Running - Mechanisms and Strategies

The aim of this thesis was to analyse strategies to reduce muscular fatigue in trail running and potentially draw conclusions on the underlying mechanisms. Trail running is a new and upcoming sport that induces a combination of fatigue and muscle damage in the main locomotor muscles. To obtain conclusive evidence on the effect of intervention studies a preliminary descriptive study was undertaken to characterise typical fatigue and damage. Subsequently a model was developed and validated that would allow the investigation of interventions in an applied field setting. A popular current strategy in trail running is the use of compression garments; therefore the effect of these on performance was studied as an intervention. Furthermore, prior heating is anecdotally considered beneficial and recent research has suggested a potential mechanism to link this with reduced muscle damage. Therefore a controlled laboratory study was conducted, examining the effects of passive heating on functional consequences of downhill running in an untrained population. In synopsis, the research conducted for this thesis provides descriptive evidence and a validated terrain model to further investigate fatigue reduction strategies in trail running. Additionally it adds to the current literature in disproving a positive effect of compression garments on performance and demonstrating the functional link between heating and eccentric-induced muscle damage reduction

Effects of fatigue on muscle activation and shock attenuation during barefoot running

Lately, barefoot running has received attention from many acknowledged researchers and athletes alike. If alterations in running mechanics related to fatigue are found to be different while running barefoot, it may help to identify the practicality and efficacy of barefoot running in terms of injury prevention. PURPOSE: The purpose of this study was to investigate the effect of global fatigue on muscle activation and the rate of shock attenuation during barefoot (BFT) and shod (SHD) running in habitually shod runners. METHODS: Eleven well-trained runners were recruited from the community to complete protocols in two different footwear conditions (BFT and SHD). Each condition consisted of two instrumented 100-meter run trials (pre- and postfatigue) where data for the rate of tibial acceleration (RA) and preactivation iEMG of the tibialis anterior (TA) and medial gastrocnemius (MG) were gathered. Between each trial, subjects completed a 30-minute maximal effort fatiguing run in shoes on an outdoor running track. The two conditions differed only in footwear donned for the instrumented trials, were separated by 3- 7 days, and were preceded by 36 hours of non-exercise rest to reduce confounding fatigue. Three two-by-two repeated measures ANOVAs with factors Time (pre, post) and Footwear (BFT, SHD) were applied with an alpha level of 0.05. RESULTS: The results revealed a significant difference for RA based on condition. BFT yielded higher acceleration rates than SHD (1646.64 g/s vs. 650.93 g/s; p \u3c 0.001). RA for both conditions remained unchanged following fatigue, showing an equal ability to attenuate impact shock. TA iEMG responded differently to fatigue based on condition, according to a significant interaction observed (p = 0.031). Following fatigue, TA iEMG increased by 8.66% SHD and decreased by 12.54% BFT (p = 0.015). MG iEMG revealed no significant effect of time or footwear, acting in a similar fashion in all trials. CONCLUSION: Our data indicate that runners may adopt different shank muscle coordination strategies while running barefoot and shod. In addition, these strategies appear to be affected differently by fatigue in order to adequately attenuate impact shock. It may be suggested to approach barefoot running with caution, especially when an athlete is in a fatigued state

Match running performance during fixture congestion in elite soccer: Research issues and future directions

Match congestion in elite soccer has been proposed to result in residual fatigue and underperformance in ensuing competition due to insufficient recovery time. In this article, matters relating to match congestion and running performance in elite soccer competition are discussed. The authors suggest a need to determine the extent to which elite players are in reality exposed to periods of match congestion hence to potential declines in performance. Despite evidence of exercise-induced muscle damage combined with a decline in physical performance up to 72-hours post-match, research using time-motion analyses suggest running performance represented by distances covered is unaffected over periods of match congestion. The authors recommend analysis of alternative movement variables including accelerations, decelerations and turns that are taxing metabolically and contribute greatly to muscle damage. Moreover, a holistic approach combining subjective ratings with biochemical, hormonal and immunological responses to exercise would be pertinent especially in players frequently exposed to match congestion. Contemporary practitioners typically implement various post-match recovery treatments during dense schedules in an attempt to accelerate recovery and ensure that subsequent running performance is not unduly affected. However, empirical evidence to support their efficacy in maintaining running performance is lacking and the authors recommend controlled intervention studies using match simulations in an attempt to verify their effectiveness. These points are critically addressed using findings from the current scientific literature while gaps in the current body of knowledge and future directions for research are highlighted

Is it time to turn our attention toward central mechanisms for post-exertional recovery strategies and performance?

• Central fatigue is accepted as a contributor to overall athletic performance, yet little research directly investigates post-exercise recovery strategies targeting the brain • Current post-exercise recovery strategies likely impact on the brain through a range of mechanisms, but improvements to these strategies is needed • Research is required to optimize post-exercise recovery with a focus on the brain Post-exercise recovery has largely focused on peripheral mechanisms of fatigue, but there is growing acceptance that fatigue is also contributed to through central mechanisms which demands that attention should be paid to optimizing recovery of the brain. In this narrative review we assemble evidence for the role that many currently utilized recovery strategies may have on the brain, as well as potential mechanisms for their action. The review provides discussion of how common nutritional strategies as well as physical modalities and methods to reduce mental fatigue are likely to interact with the brain, and offer an opportunity for subsequent improved performance. We aim to highlight the fact that many recovery strategies have been designed with the periphery in mind, and that refinement of current methods are likely to provide improvements in minimizing brain fatigue. Whilst we offer a number of recommendations, it is evident that there are many opportunities for improving the research, and practical guidelines in this area

The influence of contextual factors on running performance in female Australian football match-play

The influence of contextual factors on running performance in female Australian football match-play. J Strength Cond Res 33(9): 2488–2495, 2019—Given the recent growth of the professional status among multiple female football codes, the aim of this study is to investigate the effects of contextual factors on activity profiles and pacing strategies in female Australian football (AF) players. Thirty-five female AF players participated in this study. Global positioning system analysis was completed over 1 competitive season. Matches were separated into eight 10-minute periods. Greater distances were covered during the first half irrespective of playing position (effect size [ES] = 0.39–0.50, Likelihood ≥90%). Throughout a number of periods half-backs (defensive players) covered greater distances during losses (ES ≥ 0.74, Likelihood ≥92%) and against top 3 opponents (ES ≥ 1.0, Likelihood ≥97%). Midfielders and half-backs covered greater distances (ES ≥ 0.49, Likelihood ≥89%) in the final match period in winning compared with losing matches. A reduction in player work rate is evident during the second half of matches. The influence of contextual factors varied across positional groups. However, it is clear that coaches could use player rotation both early in the match in an attempt to delay the effect of fatigue and more frequently during the second half to increase running intensity

Psychological determinants of whole-body endurance performance

Background: No literature reviews have systematically identified and evaluated research on the psychological determinants of endurance performance, and sport psychology performance-enhancement guidelines for endurance sports are not founded on a systematic appraisal of endurance-specific research. Objective: A systematic literature review was conducted to identify practical psychological interventions that improve endurance performance and to identify additional psychological factors that affect endurance performance. Additional objectives were to evaluate the research practices of included studies, to suggest theoretical and applied implications, and to guide future research. Methods: Electronic databases, forward-citation searches, and manual searches of reference lists were used to locate relevant studies. Peer-reviewed studies were included when they chose an experimental or quasi-experimental research design, a psychological manipulation, endurance performance as the dependent variable, and athletes or physically-active, healthy adults as participants. Results: Consistent support was found for using imagery, self-talk, and goal setting to improve endurance performance, but it is unclear whether learning multiple psychological skills is more beneficial than learning one psychological skill. The results also demonstrated that mental fatigue undermines endurance performance, and verbal encouragement and head-to-head competition can have a beneficial effect. Interventions that influenced perception of effort consistently affected endurance performance. Conclusions: Psychological skills training could benefit an endurance athlete. Researchers are encouraged to compare different practical psychological interventions, to examine the effects of these interventions for athletes in competition, and to include a placebo control condition or an alternative control treatment. Researchers are also encouraged to explore additional psychological factors that could have a negative effect on endurance performance. Future research should include psychological mediating variables and moderating variables. Implications for theoretical explanations of endurance performance and evidence-based practice are described

Physical and mental fatigue reduce psychomotor vigilance in professional football players

PURPOSE: Professional football players experience both physical and mental fatigue. The main aims of this randomized crossover study were to investigate the effect of mental fatigue on repeated sprint ability (RSA), and the effects of both physical and mental fatigue on psychomotor vigilance.METHODS: Seventeen male professional football players performed maximal 20-m shuttle sprints interspaced by incomplete recovery (RSA test). Running speed, heart rate (HR), brain oxygenation and rating of perceived exertion (RPE) were monitored during each sprint. The RSA test was preceded by either a 30-min Stroop task to induce mental fatigue (MF), or by watching a documentary for 30 min (CON) in a randomized counterbalanced order. Participants performed a psychomotor vigilance test (PVT) at baseline, after the cognitive task (MF or CON), and after the RSA test.RESULTS: HR and RPE significantly increased, while running speed and brain oxygenation significantly decreased over the repeated sprints (p < 0.001) with no significant differences between conditions. Response speed during the PVT significantly declined after the Stroop task but not after CON (p = 0.001). Response speed during the PVT declined after the RSA test in both conditions (p < 0.001) and remained lower in the MF condition compared to CON (p = 0.012).CONCLUSIONS: Mental fatigue does not reduce RSA. However, the results of this study suggest that physical and mental fatigue have negative and cumulative effects on psychomotor vigilance. Therefore, strategies to reduce both physical and mental fatigue should be implemented in professional football players

Avoiding the Pheidippides effect : how theories contribute to endurance trail practice

Ultra endurance sport has shown a significant increase during the last couple of decades. This paper focuses on theories which explain the phenomenal efforts ultra endurance athletes face when running extreme distances. These ultra athletes have to endure physical pain and mental distress for long hours or even days before crossing the finishing line. This extreme running on technical terrain requires considerable physiological effort (Millet, Hoffman, & Morin, 2012). Freund et al. (2012), states that as a consequence of running such distances, runners will experience muscle soreness, cramps, ruptured muscle fibres that lead to myalgia and myofascial pain, compartment syndrome, inflammation of tendons and joint capsules, and fatigue fractures. And yet, none of them succumb to their injuries or exhaustion under normal conditions, as in the case of Pheidippides. Various theories argue that the body is a high functioning machine which depends on physical measures to determine its efficiency while others put the brain as central to endurance practice and argue that the brain is the ultimate regulator which is there to protect the body. The athlete can never be harmed as the brain is taking measures so that body systems are never in distress. The beating heart is protected and catastrophe cannot occur. This paper illustrates various diverse theories which posit different arguments regarding extreme running and how it is actually achievable, without the athlete perishing due to the effort.peer-reviewe

THE RELATIONSHIP BETWEEN MUSCULOSKELETAL STRENGTH, PHYSIOLOGICAL CHARACTERISTICS, AND KNEE KINESTHESIA FOLLOWING FATIGUING EXERCISE

Fatiguing exercise may result in impaired functional joint stability and increased risk of unintentional injury. While there are several musculoskeletal and physiological characteristics related to fatigue onset, their relationship with proprioceptive changes following fatigue has not been examined. The purpose of this study was to establish the relationship between musculoskeletal and physiological characteristics and changes in proprioception, measured by threshold to detect passive motion (TTDPM), following fatiguing exercise. Twenty, physically active females participated (age: 28.65 ± 5.6 years, height: 165.6 ± 4.3 cm, weight: 61.8 ± 8.0 kg, BMI: 22.5± 2.3 kg/m2, BF: 23.3 ± 5.4%). During Visit 1, subjects completed an exercise history and 24-hour dietary questionnaire, and body composition, TTDPM familiarization, isokinetic knee strength, and maximal oxygen uptake/lactate threshold assessments. During Visit 2, subjects completed TTDPM and isometric knee strength testing prior to and following a fatiguing exercise protocol. Wilcoxon signed rank tests determined TTDPM and isometric knee strength changes from pre- to post- fatigue. Spearman’s rho correlation coefficients determined the relationship between strength and physiological variables with pre- to post-fatigue changes in TTDPM and with pre-fatigue and post-fatigue TTDPM in extension and flexion (α=0.05). No significant differences were demonstrated from pre-fatigue to post-fatigue TTDPM despite a significant decrease in isometric knee flexion strength (P<0.01) and flexion/extension ratio (P<0.05) following fatigue. No significant correlations were observed between strength or physiological variables and changes in TTDPM from pre- to post-fatigue in extension or flexion. Flexion/extension ratio was significantly correlated with pre-fatigue TTDPM in extension (r=-0.231, P<0.05). Peak oxygen uptake was significantly correlated with pre-fatigue (r=-0.500, P<0.01) and post-fatigue (r=-0.520, P<0.05) TTDPM in extension. No significant relationships were demonstrated between musculoskeletal and physiological characteristics and changes in TTDPM following fatigue. The results suggest that highly trained individuals may have better proprioception, and that the high fitness level of subjects in this investigation may have contributed to absence of TTDPM deficits following fatigue despite reaching a high level of perceptual and physiological fatigue. Future studies should consider various subject populations, other musculoskeletal strength characteristics, and different modalities of proprioception to determine the most important contributions to proprioceptive changes following fatigue

Effects of deceptive running speed on physiology, perceptual responses, and performance during sprint-distance triathlon

Objective This study examined the effects of speed deception on performance, physiological and perceptual responses, and pacing during sprint-distance triathlon running. Methods Eight competitive triathletes completed three simulated sprint-distance triathlons (0.75 km swim, 20 km bike, 5 km run) in a randomised order, with swimming and cycling sections replicating baseline triathlon performance. During the first 1.66 km of the run participants maintained an imposed speed, completing the remaining 3.33 km as quickly as possible. Although participants were informed that initially prescribed running speed would reflect baseline performance, this was true during only one trial (Tri-Run100%). As such, other trials were either 3% faster (Tri-Run103%), or 3% slower (Tri-Run97%) than baseline during this initial period. Results Performance during Tri-Run103% (1346 ± 108 s) was likely faster than Tri-Run97% (1371 ± 108 s), and possibly faster than Tri-Run100% (1360 ± 125 s), with these differences likely to be competitively meaningful. The first 1.66 km of Tri-Run103% induced greater physiological strain compared to other conditions, whilst perceptual responses were not significantly different between trials. Conclusions It appears that even during ‘all-out’ triathlon running, athletes maintain some form of ‘reserve’ capacity which can be accessed by deception. This suggests that expectations and beliefs have a practically meaningful effect on pacing and performance during triathlon, although it is apparent that an individual’s conscious intentions are secondary to the brains sensitivity to potentially harmful levels of physiological and perceptual strain