Warm-Up Practices in Elite Snowboard Athletes - Human Kinetics

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elite snowboard athletes and evaluate their physiological impact before competition. Methods. Subjects. Four national-team athletes (2 female) were monitored ...
International Journal of Sports Physiology and Performance, 2012, 7, 295-297 © 2012 Human Kinetics, Inc.

Warm-Up Practices in Elite Snowboard Athletes Ben C. Sporer, Anita Cote, and Gordon Sleivert Purpose: The purpose of this project was to observe current warm-up practices in snowboard athletes and evaluate their physiological impact before competition. Methods: An observational design was used to monitor 4 athletes (2 female) at an Open National Snowboard Cross Championships. Activity patterns, core temperature, heart rate (HR), and time between warm-up and competition were measured. Athlete ratings of thermal comfort (TC) and thermal sensation (TS) were recorded before competition. Results: Significant barriers and challenges to an optimal warm-up included delays, environment, and logistics. Time gaps between structured warm-up and competition start time were in excess of 1 h (median = 68.8 min). Median average HR for 10 min (HR10) did not exceed 120 beats/min in the hour preceding competition, suggesting a suboptimal warmup intensity. Athletes rated their TC between comfortable and slightly uncomfortable and TS as neutral to slightly warm before the start of qualifications and finals. Conclusions: The observations of this project suggest significant gaps in current warm-up strategies used in snowboarding. These include inadequate general aerobic warm-up (based on intensity and duration), excessive time between warm-up and competition, and lack of a consistent and structured warm-up protocol. Future work is needed to evaluate the effectiveness of different warm-up strategies on muscle temperature and performance while determining the optimal length of time between warm-up and competition. Keywords: preparation, core temperature, winter sport A warm-up acts as a means to prime the body for impending training or competition.1 The proposed benefits of a physically active warm-up include an elevated baseline oxygen consumption, greater compliance of muscles and joints, and enhancements to anaerobic metabolism, contractile performance of skeletal muscle, and nerve conduction.2 Many athletes are not able to selfdetermine the intensity required for an optimal warm-up.3 For winter sports, the potential for an inadequate warm-up is likely amplified given the exposure of athletes to environmental conditions including subzero temperatures. To date, very little research has been done to evaluate warm-up practices in winter sports. The purpose of this project was to observe current warm-up strategies of elite snowboard athletes and evaluate their physiological impact before competition.

Methods Subjects Four national-team athletes (2 female) were monitored for self-determined warm-up routines at an Open National Snowboard Cross Championships. Informed consent

and all aspects of data collection and management were conducted in accordance with the Declaration of Helsinki.

Methodology Measurements included core temperature, heart rate (HR), and activity patterns before competition. Athletes ingested a thermister capsule the day of competition before eating breakfast for measurement of core temperature (Vital Sense, Mini Mitter Inc, Bend, OR). HR was collected via chest strap and transmitted to a watch receiver (S610, Polar Electro, Kempele, Finland). Temperature was recorded each minute, while HR was collected in 15-second samples and averaged every minute. Warm-up gap time (GAP) was determined as the time between the end of any structured warm-up longer than 5 minutes (or last training run if no warm-up) and the beginning of competition. Athletes were asked to rate both thermal comfort (TC) and thermal sensation (TS) immediately before the start of a qualification or finals run.4 Observations were recorded and time-stamped using a digital recorder. Temperature, HR, and observational data-recording devices were time-synched for data matching.

Data Analysis The authors are with the Human Performance Laboratory, Sport Service MAPEI, Castellanza, Italy.

Descriptive statistics (median and range) were calculated for all variables measured. HR was averaged for each 10-minute block preceding competition (HR10).

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Results The observed environment for qualifications was –2°C to 2°C with cloudy skies, while for finals it was 5°C to 7°C and partly sunny. Only 1 athlete had a GAP before competition of less than 60 minutes (~50 min). Median GAP was 68.8 minutes. A sample warm-up from a single athlete is shown in Table 1. Median HR10 and core temperature before qualifications and finals are shown in Table 2. Median TC and TS

Table 1  Sample Activity Log Before Competition in Finals Time point 11:52:43 11:57:43 12:16:14 12:34:47 12:38:02 12:40:30 12:44:03 12:45:04 12:47:45 12:56:51 13:00:19 13:01:03 13:04:06 13:04:51 13:05:10 13:05:36 13:08:03 13:20:59 13:22:49 13:31:47 13:32:08 13:38:05 13:40:50 13:45:05 13:47:45 13:50:00 13:56:01 13:58:58 14:02:00 14:02:30 14:03:59 14:06:59 14:08:00 14:08:51

Change in activity Start getting ready to go outside Leaving lodge for hill Boarding to event and inspection Arrived back at top Standing around at top Adjusting gear Putting boots and board on Training run Sun coming out and wind dying down Arrived back at top Practice technical feature Walking back up to start Sitting and putting on bindings In start gate Practice technical feature Walking back up to start In start gate Back at top Changing board again Waiting off to side visualizing Took a layer off Watching start of race Standing around start area waiting for first set of heats Doing some dynamic movements Doing some drop-squats and reaction-time warm-up Back in start area getting focused Doing some movements with drop-squats Visualizing and waiting Putting board on Seated on snow In start gate, waiting Step back out of gate for delay In gate, ready to go Started

Note: Items logged only when there is a visual change in activity.

were 1.0 (comfortable) and 5.5 (neutral to slightly warm), respectively, for qualifications and 1.0 (comfortable) and 6.0 (slightly warm) for finals.

Discussion Our observations indicate significant gaps including inadequate general aerobic warm-up (based on intensity and duration), excessive time between warm-up and competition, and lack of a consistent and structured warm-up protocol. Moderate aerobic exercise of 10 to 20 minutes has been shown to increase muscle temperature and enhance energy production at the start of subsequent activity.5 In the current study, at no time in the 60 minutes before competition was HR sustained for periods of 10 minutes or more at the minimum suggested intensity needed to prime the aerobic system. Given the ability of the central circulation to act as a heat sink for increases in muscle temperature, a rise in core temperature of ~0.5°C to 1°C after adequate warmup could reasonably be expected. Although the increase observed in the 60 minutes before finals was ~0.5°C (Table 2), this was likely due to behavioral and environmental factors rather than actual warm-up. After qualification runs, athletes stood at the bottom of the course to observe their competitors, often while wearing only race clothing (no outerwear) and therefore likely lowering core temperature and increasing peripheral vasoconstriction. Before the start of finals, an increase in air temperature (~5°C) and the addition of clothing may have increased core temperatures while physical warm-up was limited. Thus, in subzero temperatures behavior modification alone may not be adequate to maintain body temperature. It is worth noting that core temperature is not necessarily representative of muscle temperature. While muscle temperature was not measured, given the observed activity levels and sustained intensities, it is questionable whether optimal increases in muscle temperature would have occurred.6 We recommend that modifications be made to current warm-up practices to include sustained exercise (at least 10 min) within 10 to 15 minutes of competition. In conclusion, our observations suggest that warm-up practices in elite snowboard athletes may be suboptimal. Future work is needed to evaluate the effectiveness of different warm-up strategies on muscle temperature and performance while determining the optimal length of time between warm-up and competition.

References 1. Bishop D. Warm up II: performance changes following active warm up and how to structure the warm up. Sports Med. 2003;33(7):483–498. PubMed doi:10.2165/00007256-200333070-00002 2. Bishop D. Warm up I: potential mechanisms and the effects of passive warm up on exercise performance. Sports Med.

Warm-Up Practices in Winter Sport   297

Table 2  Heart Rate and Core Temperature Before and During Competition Qualifications   Heart rate    median    range   Core temperature    median    range Finals   Heart rate    median    range   Core temperature    median    range

Competition

10 min

20 min

30 min

40 min*

50 min

60 min

140 45

118 23

105 28

103 52

98 26

102 48

115 21

37.8 0.5

37.7 0.9

37.7 0.8

37.7 0.5

37.8 0.3

— —

37.9 0.2

168 13

119 27

111 23

120 30

115 30

110 17

110 23

38.0 0.6

37.9 0.4

37.7 0.4

37.7 0.4

37.6 0.7

— —

37.4 0.4

Note: HR was averaged every 10 min before competition. *Core temperature values are at 45 min prior.

2003;33(6):439–454. PubMed doi:10.2165/00007256200333060-00005 3. Mandengue SH, Seck D, Bishop D, Cisse F, Tsala-Mbala P, Ahmaidi S. Are athletes able to self-select their optimal warm up. J Sci Med Sport. 2005;8(1):26–34. PubMed doi:10.1016/S1440-2440(05)80021-0 4. Gagge AP, Stolwijk JA, Hardy JD. Comfort and thermal sensations and associated physiological responses at various ambient temperatures. Environ Res. 1967;1(1):1–20. PubMed doi:10.1016/0013-9351(67)90002-3 5. Campbell-O’Sullivan SP, Constantin-Teodosiu D, Peirce N, Greenhaff PL. Low intensity exercise in humans

accelerates mitochondrial ATP production and pulmonary oxygen kinetics during subsequent more intense exercise. J Physiol. 2002;538(Pt 3):931–939. PubMed doi:10.1113/ jphysiol.2001.013238 6. Mohr M, Krustrup P, Nybo L, Nielsen JJ, Bangsbo J. Muscle temperature and sprint performance during soccer matches—beneficial effect of re-warm-up at half-time. Scand J Med Sci Sports. 2004;14:156–162. PubMed doi:10.1111/j.1600-0838.2004.00349.x