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Influence of Environmental Conditions on Performance and Heart Rate Responses to the 30-15 Incremental Fitness Test in Rugby Union Athletes

Natera, Alex O.W.1; Jennings, Jacob1; Oakley, Aiden J.1; Jones, Thomas W.1,2

The Journal of Strength & Conditioning Research: February 2019 - Volume 33 - Issue 2 - p 486–491
doi: 10.1519/JSC.0000000000001865
Original Research

Natera, AOW, Jennings, J, Oakley, AJ, and Jones, TW. Influence of environmental conditions on performance and heart rate responses to the 30-15 incremental fitness test in rugby union athletes. J Strength Cond Res 33(2): 486–491, 2019—The purpose of this study was to examine the differences in performance and heart rate (HR) responses between a high heat outdoor condition (34.0° C, 64.1% humidity) and a temperate indoor condition (22.0° C, 50.0% humidity) during the 30-15 intermittent fitness test (30-15IFT). Eight highly trained Rugby Union players (28.1 ± 1.5 years, 181.4 ± 8.8 cm, 88.4 ± 13.3 kg) completed the 30-15IFT in 2 different temperature conditions. Dependent variables recorded and analyzed included: final running speed of the 30-15IFT, HR at rest (HR rest), maximum HR (Max HR), HR recovery, average HR (HR ave), and submaximal HR corresponding to 25, 50, and 75% of final test speed (HR 25%, HR 50%, and HR 75%) and HR at 13 km·h−1 (HR 13 km·h−1). Greater running speeds were achieved when the test was conducted indoors (19.4 ± 0.7 km·h−1 vs. 18.6 ± 0.6 km·h−1, p = 0.002, d = 1.67). Average HR and HR 13 km·h−1 were greater when the test was conducted outdoors (p ≤ 0.05, d > 0.85). Large effect sizes were observed for the greater HR at submaximal intensities (d > 0.90). The results of this study highlight the influence of temperature on 30-15IFT performance and cardiac responses. It is recommended that prescription of training based on 30-15IFT results reflects the temperature that the training will be performed in and that practitioners acknowledge that a meaningful change in assessment results can be the result of seasonal temperature change rather than training-induced change.

1Department of Sport Sciences, ASPIRE Academy for Sports Excellence, Doha, Qatar; and

2Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle upon Tyne, United Kingdom

Address correspondence to Dr. Thomas W. Jones,

Copyright © 2019 by the National Strength & Conditioning Association.