Understanding the time course effects of neuromuscular fatigue from anaerobic exercise : implications for periodisation and performance

Abstract

This thesis aims to investigate the impact of neuromuscular fatigue (NMF) derived from anaerobic exercise. A review of the literature (chapter 2) highlighted that to date there has been limited research conducted on the impact that anaerobic exercise has on NMF, how long NMF from anaerobic exercise lasts, or how individuals respond to NMF following anaerobic exercise. To investigate these concepts this thesis involves a series of studies that explore the acute and longitudinal time course responses of NMF through a variety of anaerobic exercise modalities, including both conditioning and resistance training. The first experimental chapter of this thesis (chapter 3) aimed to assess the reliability and levels of agreement between the Individualised Neuromuscular Quality of Life (INQoL) questionnaire and a novel four question Neuromuscular Fatigue Questionnaire (NMFQ). These questionnaires are designed to subjectively assess perceived neuromuscular status, which builds knowledge on how individual responses to training. The NMFQ produced similar scores to the previously validated INQoL questionnaire, indicating that this may be an appropriate tool to subjectively assess and monitor neuromuscular fatigue status from exercise in a time efficient manner in conjunction with other monitoring tools. It would be beneficial to explore the use of the NMFQ in an athletic cohort, however unfortunately that was unable to be done a part of this thesis. Neuromuscular fatigue induced by high intensity repeated effort exercise has been poorly described, thus in chapter 4 the magnitude and time course of NMF induced by a low, moderate and high repeated sprint running sessions was assessed. Recreationally active participants completed three repeat sprint running protocols in a counterbalanced, randomised order. Repeated measures of countermovement jump (CMJ), squat jump (SJ) and isometric mid-thigh pull (IMTP) accompanied each trial, at times immediately prior, immediately post, 0.5, 1, 3, 6, 24 and 48 hrs following the condition. A sinusoidal recovery response was observed with initial nadir immediately post and a primary super-compensation 3-6 hrs post for jump height, peak force and mean velocity for CMJ and SJ and peak force for IMTP. Large effect sizes were seen over time across all variables and a mixed response was observed between conditions. The application of this knowledge of time course of recovery following sessions of different intensities allows coaches to periodise training schedules more effectively to maximise adaptation. International long haul air travel is a necessity for many highly trained athletes as part of their training or competition schedules, however long haul travel is associated with an impaired neuromuscular function. Chapter 5 in this thesis sought to assess the impact of westbound trans-meridian travel on changes in CMJ performance in highly trained aerobic athletes as this is a frequently assessed monitoring tool of athletes’ lower body neuromuscular status. Elite rowers undertook a westbound flight incurring 22 hrs of flight time with 30 hrs of total travel time across nine time zones. Athletes completed a single set of 6 loaded CMJ repetitions prior to and post travel with performance measured using a digital optical encoder attached to a 20kg barbell. Each CMJ repetition was assessed for mean concentric velocity, jump height, eccentric displacement, jump height:dip ratio, mean power and mean eccentric velocity, with a comparison then made between mean set changes pre and post travel. Small to moderate changes were observed in all variables following westbound travel. These changes may be due to athletes’ retaining a high training load prior to travel resulting in the athletes being in a fatigued state, while the travel time worked as a forced recovery period. Reductions in CMJ performance are likely following westbound travel, however this may be impacted by training fatigue prior to travel that may confound CMJ performance as a monitoring metric. It is important to assess NMF from a variety of anaerobic exercise modalities including both conditioning and resistance training. Chapter 6 of this thesis assessed changes in velocity, displacement and power using loaded CMJ’s between pre-competition and competition mesocycles and chapter 7 explored this same relationship over an eight-month competition season in elite male rowers. These elite rowers completed regular training consisting of a combination of on-water rowing, rowing ergometer and resistance training sessions. Athletes completed a single set of 6 loaded CMJ’s in the first and final week of each training block with performance measured using a digital optical encoder attached to a 20kg barbell. Each set of CMJ’s were assessed for jump height (JH), eccentric displacement, mean velocity (MV), eccentric mean velocity (EMV) and mean power. The impact of an athlete’s relative strength as defined by key lift benchmarks and was used in a further analysis to understand whether changes between and within mesocycles was influenced by this metric. The results from these chapters indicate that increases in intensity have a greater negative impact on elite rowers, as opposed to high volume low-moderate intensities loads. When assessing differences between strength standards, velocity-based variables may provide a more precise indication of NMF than displacement and power variables. Overall this thesis demonstrates the acute and longitudinal time course of neuromuscular fatigue from various anaerobic exercise modalities in recreationally trained participants and elite athletes. This thesis highlights the sinusoidal recovery pattern of NMF following different repeat sprint running loads using changes in IMTP, SJ and CMJ. The findings of this thesis explored changes in loaded CMJ in elite male rowers post long haul travel, between pre-competition and competition mesocycles and over a competition season. Changes in CMJ following long haul travel was not as pronounced as expected, possibly due to maintenance of a high training load prior to travel. Changes in CMJ between training mesocycles and across a competition season indicated that increases in training intensity, as opposed to volume, had a greater impact on elite male rowers. The findings of this thesis can be implemented by strength and conditioning coaches to assist in their planning and periodisation of training.

Date of Award	2019
Original language	English
Supervisor	Nick BALL (Supervisor), Andrew MCKUNE (Supervisor) & Dale Chapman (Supervisor)