The Utility of Strength-Based Exercise for Middle- and Long-Distance Runners

Middle- and long-distance running performance is constrained by the complex interaction of physiological, biomechanical and neuromuscular factors. Several of these factors have the potential to be enhanced both acutely and chronically using strength-based exercise. A plethora of research has investigated the efficacy of strength training (ST) activities for improving physiological determinants of performance via enhancements in neuromuscular- and tendon-related properties. This body of literature has previously not been reviewed, nor is it known the extent to which the distance running community engage with ST. Moreover, research is specifically lacking in the post-pubertal adolescent age group and very few works have considered whether strength-based exercise could acutely potentiate performance-related outcomes. The first aim of this thesis was to systematically review the literature on ST for distance runners. Based upon findings from 26 studies, it was evident that ST activities have the capability of improving time-trial performance, running economy (RE) and important anaerobic qualities following a 6-14 week intervention. Despite these findings, it is uncertain what proportion of runners include ST in their routine, and whether runners of a specific age and competitive status are more likely to participate. The second study of this thesis aimed to explore ST practices of competitive distance runners (n=667). The most common activities utilised were stretching (86.2%) and core stability exercises (70.2%), despite limited evidence for their value. Resistance training and plyometric training (PT) were used by 62.5% and 35.1% of runners respectively. A disproportionately high number of under-17 and under-20 year old runners included PT, running drills and circuit training in their training, compared to older age groups. Indeed, ST is recommended for adolescent athletes to develop a wide-range of physical competencies, lower injury risk and enhance performance. A test-retest reliability investigation was conducted (Study 3) in a group of adolescent distance runners, to ascertain the reproducibility of a range of important physiological and biomechanical variables related to distance running performance and strength outcomes. Following allometric scaling of variables influenced by body mass, reliability indices showed a high level of reproducibility across all physiological parameters and maximal speed (typical error ≤ 2%; intra-class correlation coefficient > 0.8; effect size (ES) < 0.6). Biomechanical metrics displayed moderate levels of inter-session consistency. Minimal detectable change values (95% confidence) were calculated to provide a robust threshold for identifying magnitude based inference terms in subsequent studies. Study 4 investigated the effect of a ten week ST programme on a group of post-pubertal adolescent distance runners. Participants were randomly assigned to a group that added two weekly ST sessions to their training, or a control group, who continued their normal running. ST enhanced RE by a small extent (ES: 0.31-0.51) and was highly likely to improve maximal speed without deleterious effects on body composition and other aerobic parameters. The final study of this thesis investigated the efficacy of a short bout of strength-based exercise on physiological parameters and time to exhaustion (TTE) in a group of high-performing adolescent runners. Seventeen young male distance runners performed a baseline assessment session followed by two identical trials organised in a randomised crossover design. Prior to each trial, participants completed either six depth jumps (DJ) or a control condition. The DJ condition produced moderate significant improvements (-3.7%, p 0.05). In conclusion, the addition of ST to the training routine of a middle- or long-distance runner appears to provide a performance advantage via improvements in RE and anaerobic factors. Despite these well-established benefits of ST, competitive runners tend to prefer other non-running based training techniques under the impression they lower injury risk and improve performance. Importantly, results from studies 4 and 5 in this thesis have shown that in the post-pubertal adolescent age-group, both chronic (ten week) and acute strength-based exercise interventions provide a small to moderate but possibly beneficial effect on RE.