Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
The effects of water ingestion on high intensity cycling performance in a moderate ambient temperature
Eight endurance~trained cyclists rode as far as possible in 1 h on a stationary cyclesimulator in a moderate environment (20°C, 60% relative humidity, 3 m/s wind speed) while randomly receiving either no fluid (NF) or attempting to replace their ~1.7 l sweat loss measured in a previous 1 h familiari...
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
MRC/UCT RU for Exercise and Sport Medicine
2018
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613286525042688 |
|---|---|
| access_status_str | Open Access |
| author | Robinson, Tracy Anne |
| author2 | Hawley, John |
| author_browse | Hawley, John Robinson, Tracy Anne |
| author_facet | Hawley, John Robinson, Tracy Anne |
| author_sort | Robinson, Tracy Anne |
| collection | Thesis |
| description | Eight endurance~trained cyclists rode as far as possible in 1 h on a stationary cyclesimulator in a moderate environment (20°C, 60% relative humidity, 3 m/s wind speed) while randomly receiving either no fluid (NF) or attempting to replace their ~1.7 l sweat loss measured in a previous 1 h familiarisation performance ride at ~85% of peak oxygen uptake (VO₂ peak) with artificially sweetened, coloured water (F). During F the cyclists drank 1.49 ± 0.14 1 (values are mean± SEM), of which 0.27 ± 0.08 1 remained in the stomach at the end of exercise and 0.20 ± 0.05 1 was urinated after the trial. Thus, only 1.02 ± 0.12 l of the ingested fluid was available to replace sweat losses during the 1 h performance ride. That fluid decreased the average heart rate from 166 ± 3 to 157 ± 5 beats/min (P < 0.0001) and reduced the final serum [Na+] and osmolalities from 143 ± 0.6 to 139 ± 0.6 mEq/1 (P < 0.005) and from 294 ± 1.7 to 290 ± 1.9 mOsm/1 (P = 0.05), respectively. Fluid ingestion did not attenuate rises in plasma anti diuretic hormone and angiotensin concentrations, or decrease the ~-15% falls in estimated plasma volume in the F and NF trials. Nor did fluid ingestion significantly effect the ~1.7 l/h sweat rates, the rises in rectal temperature (~36.6° to 38.3°C) or the ratings of perceived exertion in the two trials. Ingestion of ~1.5 l of fluid produced an uncomfortable stomach fullness and reduced the distance covered in 1 h from 43.1 ± 0. 7 to 42.3 ± 0.6 km (P<0.05). Thus, trying to replace > 1.0 l/h sweat losses during high-intensity, short duration exercise in a moderate environment does not induce beneficial physiological effects, and may impair exercise performance. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/27033 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:43.673Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2018 |
| publishDateRange | 2018 |
| publishDateSort | 2018 |
| publisher | MRC/UCT RU for Exercise and Sport Medicine |
| publisherStr | MRC/UCT RU for Exercise and Sport Medicine |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/27033 The effects of water ingestion on high intensity cycling performance in a moderate ambient temperature Robinson, Tracy Anne Hawley, John Dennis, Steve Sports Medicine Cycling Dehydration Exertion - physiology Drinking (Physiology) Eight endurance~trained cyclists rode as far as possible in 1 h on a stationary cyclesimulator in a moderate environment (20°C, 60% relative humidity, 3 m/s wind speed) while randomly receiving either no fluid (NF) or attempting to replace their ~1.7 l sweat loss measured in a previous 1 h familiarisation performance ride at ~85% of peak oxygen uptake (VO₂ peak) with artificially sweetened, coloured water (F). During F the cyclists drank 1.49 ± 0.14 1 (values are mean± SEM), of which 0.27 ± 0.08 1 remained in the stomach at the end of exercise and 0.20 ± 0.05 1 was urinated after the trial. Thus, only 1.02 ± 0.12 l of the ingested fluid was available to replace sweat losses during the 1 h performance ride. That fluid decreased the average heart rate from 166 ± 3 to 157 ± 5 beats/min (P < 0.0001) and reduced the final serum [Na+] and osmolalities from 143 ± 0.6 to 139 ± 0.6 mEq/1 (P < 0.005) and from 294 ± 1.7 to 290 ± 1.9 mOsm/1 (P = 0.05), respectively. Fluid ingestion did not attenuate rises in plasma anti diuretic hormone and angiotensin concentrations, or decrease the ~-15% falls in estimated plasma volume in the F and NF trials. Nor did fluid ingestion significantly effect the ~1.7 l/h sweat rates, the rises in rectal temperature (~36.6° to 38.3°C) or the ratings of perceived exertion in the two trials. Ingestion of ~1.5 l of fluid produced an uncomfortable stomach fullness and reduced the distance covered in 1 h from 43.1 ± 0. 7 to 42.3 ± 0.6 km (P<0.05). Thus, trying to replace > 1.0 l/h sweat losses during high-intensity, short duration exercise in a moderate environment does not induce beneficial physiological effects, and may impair exercise performance. 2018-01-29T06:46:25Z 2018-01-29T06:46:25Z 1994 Master Thesis Masters MPhil http://hdl.handle.net/11427/27033 eng application/pdf MRC/UCT RU for Exercise and Sport Medicine Faculty of Health Sciences University of Cape Town |
| spellingShingle | Sports Medicine Cycling Dehydration Exertion - physiology Drinking (Physiology) Robinson, Tracy Anne The effects of water ingestion on high intensity cycling performance in a moderate ambient temperature |
| thesis_degree_str | Master's |
| title | The effects of water ingestion on high intensity cycling performance in a moderate ambient temperature |
| title_full | The effects of water ingestion on high intensity cycling performance in a moderate ambient temperature |
| title_fullStr | The effects of water ingestion on high intensity cycling performance in a moderate ambient temperature |
| title_full_unstemmed | The effects of water ingestion on high intensity cycling performance in a moderate ambient temperature |
| title_short | The effects of water ingestion on high intensity cycling performance in a moderate ambient temperature |
| title_sort | effects of water ingestion on high intensity cycling performance in a moderate ambient temperature |
| topic | Sports Medicine Cycling Dehydration Exertion - physiology Drinking (Physiology) |
| url | http://hdl.handle.net/11427/27033 |
| work_keys_str_mv | AT robinsontracyanne theeffectsofwateringestiononhighintensitycyclingperformanceinamoderateambienttemperature AT robinsontracyanne effectsofwateringestiononhighintensitycyclingperformanceinamoderateambienttemperature |