optimising endurance performance

Completed 2015

Carbohydrate ingestion during prolonged (>1hour) exercise is common practice. However ergogenic benefits are not widely supported by evidence of a liver or muscle glycogen sparing effect, which may be beneficial to athletes needing to perform with limited carbohydrate availability towards the end of a race. Therefore, this research aimed to consolidate the published literature by investigating a dose response effect of multiple transportable carbohydrate (glucose-fructose) ingestion during exercise. This thesis provided novel evidence that with a 90 g/h dose of glucose-fructose (2:1 ratio) during prolonged exercise, muscle glycogen can be spared, and lead to improved exercise performance. This research also demonstrated that ‘over-dosing’ exogenous carbohydrate intake and intestinal carbohydrate transport limits was detrimental to endogenous substrate oxidation and led to diminished performance.

Publications:

• King, A. J., O'Hara, J. P., Morrison, D. J., Preston, T., & King, R. (2018). Carbohydrate dose influences liver and muscle glycogen oxidation and performance during prolonged exercise. Physiol Rep, 6(1).
• King, A. J., O'Hara, J. P., Arjomandkhah, N. C., Rowe, J., Morrison, D. J., Preston, T., & King, R. (2019). Liver and muscle glycogen oxidation and performance with dose variation of glucose-fructose ingestion during prolonged (3 h) exercise. Eur J Appl Physiol, 119(5), 1157-1169.

Commenced October 2015

The ergogenic benefits of carbohydrate ingestion during endurance exercise have been reported. However, differences in substrate oxidation (exogenous and endogenous) and performance gains between cycling and running and males and females remains to be fully elucidated. Differences in the number and type of muscle fibres recruited in cycling and running suggest a potential difference in substrate utilisation during exercise which has not been fully investigated in relation to exercise performance. The female hormones progesterone and estradiol have been reported to increase preference for fat oxidation in females during exercise. Although comparisons between males and females have previously been made with equivocal findings, a well-controlled direct comparison of substrate oxidation and exercise performance with exogenous carbohydrate ingestion has yet to be made. This PhD aims to explain any metabolic and performance differences in response to carbohydrate ingestion between modes of exercise and sex. Preliminary data shows a greater improvement in cycling time trial performance compared with running when carbohydrate was ingested during exercise amongst male triathletes. This important research will hopefully provide clearer guidance on carbohydrate ingestion recommendations to optimise endurance performance.

Presentations:

• Black, A. D., King, R. F. G. J., Wilson, O. J., Lees, M., Morrison, D. J., Preston, T., Rowe, J., O’Hara, J. P. (2019). Carbohydrate ingestion is more beneficial for time trail performance in cycling than running. Physiological Society Annual Conference; Aberdeen, UK.

Commenced February 2017

The track cycling Omnium has been an Olympic event since London 2012. This research aims to provide coaches and athletes with a clearer understanding of the physiological and tactical requirements to be successful. The Omnium differs to other cycling disciplines because of the greater frequency of changes in speed therefore most of the existing models that seek to understand performance in cycling are inadequate. This research seeks to understand how the distribution of effort may differ amongst participants with varying physiological capabilities and identify the performance demands that a potential participant should be able to achieve to be successful in winning a medal.

Commenced October 2017

Exercise-induced bronchoconstriction (EIB), defined as the acute narrowing of the airway in association with exercise, is prevalent in endurance athletes due to the interaction between physiological demands and environmental irritants. Whilst athletes with EIB often report exercise impairment, limited quantitative evidence exists that may reflect methodological limitations of the performance measures employed. Understanding the impact of EIB on performance may have implications on the perceptions of asthma medication use in sport. Recently, high profile athletes have been implicated in the misuse of asthma medication for performance enhancement that may elicit medication non-adherence at the detriment to health and performance. Therefore, the aim of this thesis is to determine the impact of EIB on severe intensity domain exercise and critical power and evaluate athletes experience and perceptions of asthma medication use and anti-doping policy.

Publications:

• Anti-doping policy, therapeutic use exemption and medication use in athletes with asthma: a narrative review and critical appraisal of evidence. Allen H., Backhouse S.H., Hull J.H., Price O.J. (Sports Medicine, 2019)
• The Allergy Questionnaire for Athletes provides value in the assessment of exercise-induced bronchoconstriction. Allen H., Hull J.H, Backhouse S.H., Dickinson J.W., De Carne T., Dimitrou L., Price O.J (Allergy, 2019)

Published abstracts and conference proceedings:

• Dietary Nitrate Supplementation increases fractional exhaled nitric oxide: Implications for the assessment of airway health in athletes. Allen H., Hull J.H., O’Hara J.P., Dickinson J.W., Price O.J
• The role of fractional exhaled nitric oxide in the assessment of athletes reporting exertional dyspnoea. Allen H., Hull J.H, Backhouse S.H., Dickinson J.W., De Carne T., Dimitrou L., Price O.J (EAACI Congress 2019)
• Dietary Nitrate Supplementation increases fractional exhaled nitric oxide: Implications for the assessment of airway health in athletes. Allen H., Hull J.H., O’Hara J.P., Dickinson J.W., Price O.J (EAACI Congress 2019)
• Does the measurement of fractional exhaled nitric oxide have a role in the detection of exercise-induced bronchoconstriction in athletes? Allen H., Hull J.H., Backhouse S.H., Price O.J (British Association of Sport and Exercise Medicine Annual Conference, 2018)
• The allergy questionnaire for athletes: A simple screening tool for the assessment of exercise-induced bronchoconstriction. Allen H., Hull J.H., Backhouse S.H., Price O.J (British Association of Sport and Exercise Medicine Annual Conference, 2018.

Commenced February 2018

Athletes competing at major sporting events, were the conditions are hot-humid, often experience a reduction in exercise capacity related to hyperthermia-induced fatigue. As such, this PhD aims to develop heat-alleviating strategies which reduce the negative impact heat has on endurance performance. More specifically, heat acclimation interventions for triathletes competing at the Tokyo 2021 Olympics. In addition, this PhD is looking to develop a heat stress test to better understand individual athlete responses and monitor the effectiveness of heat-alleviating strategies. Findings from this thesis may be used by support staff and athletes prior to competition in the heat to optimise performance. This PhD is in partnership with the English Institute of Sport / British Triathlon Federation.

Presentations:

• Snape D., Wainwright B., Woods D.R., Needham L., O’Hara J. (2020). Reliability of blood biomarkers of physiological stress at rest and in response to exercise under hot-humid conditions. Future Physiology Conference 2020.

Commenced February 2018

Muscle-tendon function has been reported to be a key determinant of endurance exercise performance, specifically within the muscle-tendon unit that crosses the ankle joint as it plays such a pivotal role in the transfer of internal work to external power during cycling and running. This research uses ultrasound techniques to assess muscle-tendon function in the triceps surae group during cycling and establishes relationships between neuromuscular parameters of human movement and overall movement economy. Comparisons are to be made between triathletes and athletes who compete only in cycling or running to understand the potential chronic effects of each mode of exercise on muscle-tendon function and neuromuscular performance. In addition to enhancing the body of understanding in the fields of human locomotion and muscle function, this PhD will also have practical applications leading to the improvement of performance not only in triathlon, but also in cycling and running individually.

Publications

• Walker J., Cronin N., Jongerius N., Wainwright B., Bissas N. (2019). Effects of fascicle length filtering on muscle-tendon behaviour during cycling. ECSS Conference Presentation.
• Walker J., Bissas N., Hanley B., Wainwright B., Cronin N. (2020). Repeatability of muscle-tendon unit passive stiffness measurements: modulation of the contractile and series-elastic element. (In Press).

Commenced October 2018

Previous research in competitive sports, such as free diving and cycling, has suggested that the use of acute and chronic apnoeas (the cessation of breathing) can improve performance. During breath holds hypoxemia occurs in the spleen, potentially causing a contraction and subsequently increasing the number of circulating erythrocytes. Other physiological responses are based upon the mammalian diving response and the primary function of oxygen preservation. These responses combined with an increase in acidosis tolerance are hypothesised to lead to improved performance. This PhD focusses on the link between apnoeas and competitive swimming, exploring the possibility of finding great rewards from marginal gains.

Publications

• Robertson, C., Lodin-Sundström, A., O’Hara, J., King, R., Wainwright, B., and Barlow, M. (2020). Effects of pre-race apnoeas on 400-m freestyle swimming performance. J Strength Cond Res 34(3): 828–837.

Completed PhD 2019

Whilst the aerodynamic advantages of dedicated time-trial cycling positions are widely known, their impact on biomechanical performance is much less researched. In this project a detailed full-body skeletal model was created using data from 56 trained cyclists. Kinematic outcome variables were related to measures of reaction forces at the foot-pedal interface for a range of cycling positions. Through advanced mathematical models the mechanical effectiveness of different cycling positions were evaluated and the biomechanical factors underpinning relationships investigated. In addition, recordings of surface electromyography of the main leg muscles were collected to provide an insight into which different muscular coordination strategies are being exploited to create the movement. Finally, a range of off-bike tests created a neuromuscular profile, which helped us to better understand which muscular characteristics are crucial to enable an efficient cycling movement.

Presentations:

• Jongerius, N., Walker, J., Wainwright, B., Bissas, A. (2018) Differences in Strength & Power profiles between Road and Time Trial cyclists. Science & Cycling 2018 conference.
• Jongerius, N., Wainwright, B., Bissas, A. (2018) A comparison of marker set use in assessing kinematic variables in cycling. 23rd Annual Congress of the European College of Sports Science.