Cycling Time-trial Performance in Hot Conditions

PhD Thesis


Bayne, F. (2023). Cycling Time-trial Performance in Hot Conditions. PhD Thesis London South Bank University School of Applied Sciences https://doi.org/10.18744/lsbu.941v9
AuthorsBayne, F.
TypePhD Thesis
Abstract

The overall aim of this thesis was to investigate the effect of cold-water ingestion and pouring on 30min cycling time-trial performance in hot and dry, and hot and humid environmental conditions.
Study one (i) determined the impact of multiple vs single feedback on 30min cycling time-trial performance in experienced cyclists-triathletes’ and non-cyclists-triathletes’, and (ii) investigated experienced cyclists-triathletes’ information acquisition during a 30min cycling time-trial. The findings from this study highlighted that experienced cyclists-triathletes’ 30 min cycling time-trial performance was impaired with multiple feedback (227.99±42.02W) compared to single feedback (287.9±60.07 W; p < 0.05), despite adopting and reporting a similar pacing strategy and perceptual responses (p > 0.05). In addition, cyclists-triathlete’s primary and secondary objects of regard (i.e. main variable of focus) were power (64.95s) and elapsed time (64.46s). Notably, total glance time during multiple feedback decreased from the first 5 min (75.67s) to the last 5 min (22.34s) which may have resulted from a mental overload (exercise and cognitive task). The findings from this study were used to inform the subsequent studies in this PhD in an attempt to minimise any external impact on performance. Therefore, participants in study 2 and 4 were only given feedback on elapsed time whilst completing the time-trial.
Study two investigate the effect of heat (hot vs thermoneutral) and humidity (dry vs humid) on physiological and perceptual responses during a 30min cycling time-trial in experienced cyclists-triathletes. The findings from this study highlighted that performance was significantly impaired in hot and dry conditions compared to thermoneutral/control conditions (177.35±1.68W vs 236.86±1.83W). This impairment was accompanied by a higher Trectal and thermal discomfort ratings during the TT. Trectal was significantly greater in hot (38.05±0.15°C) compared to control (38.55±0.04°C) throughout the TT p=0.001). Thermal comfort ratings were also significantly lower in thermoneutral/control (0±0(0%)) compared to hot (12±2(60%)) during the TT (p = 0.003). Secondly, power was also significantly impaired in hot and humid compared to thermoneutral/control conditions (160.12±3.43W vs 235±2.48W; p=0.001). This impairment was accompanied by a higher Trectal and thermal discomfort ratings during the TT. Trectal was significantly greater in hot (38.85±0.09°C) compared to control (38.55±0.12°C) throughout the TT (p=0.004). Thermal comfort ratings were also significantly lower in thermoneutral/control (0±0(0%)) compared to hot (19±3(95%)) during the time-trial (p = 0.001). Thirdly, power was significantly impaired in hot and humid compared to hot and dry (160.12±3.43W vs 177.35±1.68W, p =0.038). This impairment was accompanied by a higher Trectal and thermal discomfort ratings during the TT. Trectal was significantly greater throughout the TT in hot and humid (38.7±0.09°C) compared to hot and dry (38.49±0.07°C; p = 0.043). Thermal comfort ratings were significantly higher in hot and humid compared to hot and dry during the TT (19±3(95%)) vs 12±2(60%)); p = 0.029). Overall, cycling power output was significantly impaired in hot and dry and hot and humid conditions compared to thermoneutral conditions, and hot and humid conditions caused a greater impairment to cycling power output compared to hot and dry conditions. All impairments were accompanied by a greater thermal strain (physiological (rectal temperature) and/or perceptual responses (thermal comfort)). The findings from this study highlight an impairment in cycling performance in hot conditions (dry and humid) and therefore athletes should use heat alleviation strategies to minimise this impairment.
Study three investigated (i) the level of perceived heat strain cyclists-triathletes (recreational, competitive and professional) experience during competitions in hot conditions, (ii) which heat alleviation strategies (i.e. hydration and cooling) athletes use during competitions in hot conditions, and (iii) whether or not these strategies are dependent on the environmental heat (i.e. dry vs humid heat). The findings from this study highlighted that the type of per cooling strategies currently employed by competitive and professional cyclists-triathletes during training and competition are condition (dry vs humid) dependant. Specifically, cold water ingestion was the most employed strategy in hot and dry conditions (HD), whereas a combination of cold-water ingestion and pouring was the most employed strategy in hot and humid conditions (HH). The timing of application was pre-planned based on ‘distance’ and supplemented with ‘how participants felt during’ and ‘when pit stops were available’ in HD. Whereas timing of application was pre planned based on ‘distance’ and ‘how participants felt during’ only in HH. The justification for type and timing of strategies was previous experience/perceived effectiveness (e.g., trial and error). An additional finding of this study was that competitive athletes found benefits from mental strategies, such as imagery and modelling; whereas professional athletes found benefits from positive self-talk and locus of control during competition in hot conditions. The findings from the questionnaire were used to inform the cooling methods used in study four (i.e. type of cooling, amount of cooling, frequency of cooling etc). Therefore, the two cooling methods that were used in study four were cold-water ingestion and cold-water pouring.
Study four investigated the effect of cold-water ingestion and pouring on 30min cycling time trial performance in hot and dry, and hot and humid conditions in experienced cyclists triathletes. Participants were assigned to a group; Group 1 - hot and dry, or group 2 - hot and humid. Within their group participants completed 4 x 30min cycling time-trials on separate occasions: (i) thermoneutral, (ii) hot with no cooling (dry or humid, group dependant), (iii) cold-water ingestion, and (iv) cold-water pouring. The findings from this study showed that cold-water pouring was more beneficial compared to cold-water ingestion for power output in hot and dry conditions (Mean±SD 199.40±0.82W vs 180.35±1.51W, p = 0.023). This performance benefit occurred in absence of a significant difference in rectal temperature between cold-water pouring and ingestion (38.18±0.13°C vs 38.38±0.14°C, p = p=0.121). There was also no difference in thermal comfort between cold-water pouring and ingestion (11±1(55%) vs 12±2(60%); p = 0.067). Conversely, cold-water ingestion was more beneficial compared to cold-water pouring for power output in hot and humid conditions (Mean±SD 173.77±0.97W vs 165.16±1.31W, p=0.760). This was supported by physiological responses such as rectal temperature which was significantly lower with cold-water ingestion compared to cold-water pouring (37.9±0.1°C vs 38.5±0.19°C, p = 0.001). This was also supported by perceptual responses such as mean±SD thermal comfort ratings which was significantly greater with cold-water pouring than cold-water ingestion during the time-trial in hot and humid conditions (14±3(70%) vs 12±1(60%); p = 0.004). Power in the hot and dry conditions with cold-water pouring (199.40±0.82W) was significantly greater compared to hot and humid condition with cold-water pouring (165.16±1.31W, p =0.001). This difference occurred in absence of a difference in physiological responses such as rectal temperature as there was no difference between groups respectively (38.18T ±0.13 vs 38.4±0.22, p = 0.253). However, this performance difference was supported by perceptual responses such as thermal comfort ratings which were significantly greater with cold-water pouring during the time-trial in hot and humid conditions compared to hot and dry conditions (14±3(70%) vs 12±2(60%); p = 0.021). In conclusion, cold-water pouring provided a greater ergogenic effect on 30min cycling time-trial performance in HD conditions compared to cold-water ingestion. Whereas cold-water ingestion provided a greater ergogenic effect on power output during a 30min cycling time-trial performance in HH conditions compared to cold-water pouring. Collectively, the findings from this study show that athletes and coaches should not only consider the condition (dry vs humid) but also which cooling strategy is best suited for said condition (internal vs external) when preparing for training and/or competing in hot conditions.
The distinction of the effect of hot and dry, and hot and humid conditions on 30min cycling time-trial performance and subsequent physiological, and perceptual responses are a particular novel and applicable aspect of this thesis and contribute new data and interpretations to this area of research.

Year2023
PublisherLondon South Bank University
Digital Object Identifier (DOI)https://doi.org/10.18744/lsbu.941v9
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Publication dates
Print26 May 2023
Publication process dates
Deposited30 May 2023
Additional information

This research programme was carried out in collaboration with Body Cap

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