Impact of Pre-cooling in Adolescent Athletes While Playing Tennis in Hot Conditions
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 8
- 试验地点
- 2
- 主要终点
- Heart rate
研究概览
简要总结
Many tennis tournaments are played outdoors in hot and humid conditions, which poses a significant challenge particularly for children athletes. The purpose of this investigation is to examine if a precooling method can reduce thermal strain and consequently improve the performance of adolescent tennis athletes while exercising in hot conditions.
详细描述
Matches were conducted on hard-court surfaces separated by 24h (n=4 pairs) or 144h (n=1pair) between 9am and 6pm and were played in winning two sets. Participants were paired according to their level of play and competed against the same component at the same time of the day in both matches.
Three hours before the start of their scheduled match, each player ingested a telemetric pill in order to estimate the visceral temperature. Upon arrival, all participants provided a urine sample for assessment of urine specific gravity as an indicator of their hydration status and they emptied their bladders before were weighed. They were weighed twice, at baseline and at the end of the match with a precision weight scale (Kern DE 150K2D, KERN & SOHN GmbH, Balingen, Germany). During the match the participants consumed water and any other sport drink and food ad libitum. The total weight of the players' food and fluids that was consumed was measured using a precision weight scale. If participants wished to urinate during the match, they were asked to use a urine cup and their urine was weighed.
One hour before the match, the precooling group was wearing a Cooling Cap (WElkins Sideline Cooling System, SCS) for 45 minutes. On removal from a -20oC freezer, the cap surface was 10.7±2.5oC. After 45 minutes, participants removed the cap and they performed a 5 minutes standardized warm-up (running around the court and running exercises from baseline to net and back to baseline) and 10 min tennis specific warm up (rallies and serves) on court. Each participant, before the warm-up, was outfitted with a heart rate chest strap and iBUTTON sensors at four sites of the body (chest, upper arm, thigh and calf).
The scoring and timing characteristics of the matches complied with 2016 ITF rules. Three new balls were used for each match with the players retrieving balls between points. Matches were filmed from one end of the court, using a digital video camera (Sony DCR-VX2000E PAL, Japan). Participants were performed on perceptual measurements at baseline, after each set, and at the end of the match.
Thermoregulatory, cardiovascular and perceptual responses were recorded with standardized techniques: 1) visceral temperature using telemetric pill (BodyCap, Caen, France) was continuously recorded throughout the match; 2) skin temperature using iBUTTON sensors (type DS1921 H, Maxim/Dallas Semiconductor Corp., USA) on chest, upper arm, thigh and calf was recorded continuously; 3) heart rate (HR) variability data were sampled through short-range telemetry at 1,000 Hz with a Polar RS800CX (Polar Electro , Kempele, Finland). The heart rate monitor signal will be transferred to the Polar Precision Performance Software (release 3.00; Polar Electro Oy); 4) thermal comfort (scale 1-5), thermal sensation (scale 1-10) and rating of perceived exertion using standardized questionnaires were recorded at baseline, after each set, and at the end of the match.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Prevention
- 盲法
- Single (Participant)
入排标准
- 年龄范围
- 14 Years 至 17 Years（Child）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Healthy adolescent athletes
排除标准
- •Diagnosed chronic medical condition;
- •Symptoms of acute illness;
- •Recent (past 4 weeks) usage of medications known to affect the circulatory system, the thyroid, the pituitary function, or the metabolic status.
结局指标
主要结局
Heart rate
时间窗: Up to 4 hours, during a one complete tennis match
Heart rate data were continuously monitored using a Polar Team system (Polar® Team 2, Polar Electro Oy, Kempele, Finland
Core temperature
时间窗: Up to 4 hours, during a one complete tennis match
Visceral temperature was continuously recorded throughout the match using telemetric pills (BodyCap, Caen, France)
Skin temperature
时间窗: Up to 4 hours, during a one complete tennis match
Skin temperature was continuously recorded throughout the match using iBUTTON sensors (type DS1921 H, Maxim/Dallas Semiconductor Corp., USA)
Change from baseline thermal comfort at after each set
时间窗: Change from baseline up to 1 hour after each set and up to 4 hours at the end of the match
Thermal comfort was assessed via the thermal comfort scale (1 = comfortable; 5 = extremely uncomfortable).
Change from baseline thermal sensation at after each set
时间窗: Change from baseline up to 1 hour after each set and up to 4 hours at the end of the match
Thermal sensation was assessed via the thermal sensation scale (-3 = cold; +3 = hot)
Change from baseline urine specific gravity (hydration status) at the end of each match
时间窗: Change from baseline up to 4 hours at the end of the tennis match
Urine samples was obtained to evaluate the urine specific gravity. Urine specific gravity (single assessmentno units) was assessed using a refractometer (PAL-10S, ATAGO CO., LTD., Fukaya, Saitama Prefecture, Japan). Urine color was assessed using a urine color scale
Change from baseline rating of perceived exertion at after each set
时间窗: Change from baseline up to 1 hour after each set and up to 4 hours at the end of the match
We used the Borg 20th Scale (6 = no exertion at all; 20 = maximal exertion)
Match - play characteristics (i.e., performance)
时间窗: Up to 4 hours, during a one complete tennis match
They were recorded by analyzing the video footage from the match. The quantitative performance indices assessed were: games and points won in each set and normalized to the number of games and points recorded in each set, respectively. Unforced errors, first and second serve accuracy, aces, shots per rally and direction changes in each point calculated. Point's duration, between point-duration as well the effective point time calculated. The effective point time starting with the ball toss of the serve and ending when the ball passed the player or bounced twice on court. In case of double fault, starting time recorded from the beginning of the second serve.
Relative humidity
时间窗: Up to 4 hours, during a one complete tennis match
It was measured continuously using a portable weather station (Kestrel 5500FW Fire Weather Meter Pro, USA) placed 1 meter above the ground according to the manufacturer's guidelines
Air temperature
时间窗: Up to 4 hours, during a one complete tennis match
It was measured continuously using a portable weather station (Kestrel 5500FW Fire Weather Meter Pro, USA) placed 1 meter above the ground according to the manufacturer's
Wind speed
时间窗: Up to 4 hours, during a one complete tennis match
It was measured continuously using a portable weather station (Kestrel 5500FW Fire Weather Meter Pro, USA) placed 1 meter above the ground according to the manufacturer's guidelines
Solar radiation
时间窗: Up to 4 hours, during a one complete tennis match
It was measured continuously using a portable weather station (Kestrel 5500FW Fire Weather Meter Pro, USA) placed 1 meter above the ground according to the manufacturer's guidelines. Solar radiation is measured directly by the device of portable weather station.
次要结局
未报告次要终点
研究者
Petros Dinas
Senior Researcher in human physiology
University of Thessaly