are athletes able to self-select their optimal warm up?

Are athletes able to self-select their optimal warm up?

SH Mandengue 1,5, D Seck 2, D Bishop 3, F Cisse 4, P Tsala-Mbala I & S Ahmaidi 5

1unite de Physiologie des Exercices et du Sport, Faculte des Sciences, Universite de Douala, Douala, Cameroun. 21NSEPS, Universite Cheikh Anta Diop Dakar, Dakar, Senegal. 3Team Sport Research Group,

School of Human Movement & Exercise Science, The Univeristy of Western Australia, Crawley, Western Australia. 4Laboratoire de Physiologie, d'Fxplorations Fonctionnelles et de Biologie Appliquees aux Sports, Faculte de Medecine, Universite Cheikh Anta Diop, Dakar, S~negal.

5Laboratolre EA3300 APS et Conduites Motrices: Adaptations et Readaptations, Faculte des Sciences du Sport, Univers]te de Picardie Jules Verne, Amiens, France.

This study aimed to examine whether athletes are able to self-select their optimal warm up and to propose a methodological approach in investigating the effects of warm up on performance. Nine male subjects undeiwent a free field warm up (FWU) at a self-selected intensity and duration during which heart rate (HR) and rectal temperature (Tre) were monitored. The intensity of this warm up was subsequently estimated from the HR obtained during an incremental test to determine maximal power (Pmax). Performance (cycle time to exhaustion at Pmax), HR and Tre, were then examined following either: NWU (no warm up); RWU (reference warm up based on FWU); RWU-10 {warm up intensity diminished by 10% compared to RWU); and RWIJ+10 (warm up intensity increased by 10% compared to RWU). Results showed no significant difference in HR (P= 0.37) and Tre increase (P= 0.77} between FWU and RWU. Performance improvement after warm up conditions gave RWU (56%; ie, 5/9 subjects) >RWU-10 {33%; ie, 3/9) >RWU+10 (11%; ie, 1/9) >NWU with significant differences between RWU and ~ (P < 0.01); RWU and RWU+10 (P< 0.01); RWU- 10 arid NWU (P< 0.01). A warm up intensity ranging from 54-72% Pmax, and inducing an increase in heart rate to 80 -+ 6% HRmax, was found to be optimal. While most athletes were able to self-determine the intensity of their optimal warm up, for others there is still a need for control.

(J Sci Med Sport 2005;8:1:26-34)

Introduction Warm up is a common practice in sport, and generally believed to enhance subsequent exercise performance. Studies on the effects of warm up exercise have been conducted since the first half of the 20th century 1 and have become more abundant in the last few decades 2-17. The main aim in these studies was to evaluate the effects of warm up upon subsequent physical performance. These investigations are character ised by a remarkable diversity in protocols where the forms (active or passive); modalit ies (cont inuous, d iscont inuous or intermittent); durat ion (short, moderate, long); intensit ies (low:

Are athletes able to self-select...

that warming-up at the anaerobic threshold provided more beneficial effects both on metabolic responses and on the performance than warming up below the threshold, while performance was impaired when warm up was performed above the anaerobic threshold. In addition to intensity, subsequent performance may also depend on the duration of the warm up and the intermediate pause.

These results suggest that the conflicting results reported in response to warm up are likely to be due to the diversity of warm up protocols used. In fact, warming-up is a process depending on two main variables: intensity and duration, which can both be manipulated to provide an infinite number of possibilities. It has previously been suggested that athletes, even of the same sport, submitted to the same intensity and duration of warm up may experience different effects on their performance 16. Consequently, warm up exercises should be specific in duration, intensity and modality to both individual athletes and sports. However, to date there has been little research examining how to determine an optimal, individualised warm up for athletes.

It is interesting to note that, during competition in individual sport disciplines, athletes of the same discipline and of the same level practise individualised warm up. Moreover, even in collective disciplines, it is observable that some team mates tend to dissociate and practise individual warm up routines. It is therefore of interest to examine whether the individual warm up routines of athletes do optimise performance or whether a scientific approach can be used to optimise warm up.

The aim of this investigation therefore was to propose a methodological approach to target an individualised optimal warm-up, based on self-determined intensity and duration of warm up, in contrast to the pre-determined and collectively imposed warm up approach found in the literature and the field. In addition, we wanted to examine whether or not athletes are able to self- select their optimal warm up.

Methods Subjects Nine male students of the Cheikh Anta Diop University Institute of Sport (INSEPS, Dakar, Senegal), with respective age, height and body mass: 23.7+1.9 y; 174.4_+5.4 cm and 64.3_+8.4 kg, volunteered to participate in this study after being presented with all the possible risks and benefits; all signed an informed consent statement. This investigation conformed to the code of ethics of the World Medical Association (Declaration of Helsinki). Subjects were six football players, one 10 000 m runner, one 5000 m runner and one 200 m runner. They all participated in sport practice class daily, in addition to their individual sport discipline training sessions. They were chosen among students who had participated in other investigations before, and had some familiarity with the ergocycle. They refrained from undertaking any heavy exercise on the day before each test.

Experimental approach The experimental design consisted of six tests. Tests III, IV, V and VI were scheduled in a random order for each subject. During these tests, rectal temperature was measured at rest, at the end of warm up, at the end of the

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pause and at the end of the maximal trial; heart rate was measured con- tinuously.

Test I: Free warm up in the field (FWU) Each subject was requested to warm up freely without any limitations placed on the intensity and duration. Subjects were required to reproduce as closely as possible the normal warm up that they would use before a competition for their specific sport up to a feeling of readiness and preparedness. At the end of the warm up, the duration of the intermediate pause before a competition was self-determined by the subject. During this session, heart rate was monitored and stored minute by minute using a heart rate monitor (Polar Sports Tester Accurex Plus, Finland}. Rectal temperature was measured at rest and at the end of warm up. A mean value of the heart rate was calculated and served to estimate the warm up intensity based on the second test. The field warm up duration and the intermediary pause were replicated in tests IV, V and VI.

Test II" Determinat ion of the individual max imal exhaust ing power (Pmax) and the in tens i ty of f ield warm up Subjects reported to the laboratory to undertake a progressive incremental test to exhaustion on a Monark ergocycle (Monark Ergomedic 824E, Sweden). The test was initiated at 30 W and increased 30 W every minute until the subject could not complete a given work level. The last load completed was considered as the individual maximal exhausting power (Pmax). During this test, HR was monitored minute by minute and the power corresponding to the mean heart rate value calculated during the FWU (Test 1) was determined. A reference warm up (RWU) was thus established by the duration of self-chosen field warm up (Test I) and the power located during the incremental exercise test (Test II).

Test III: Maximal exerc ise trial w i thout warm up (NWU) Each subject rode to exhaustion {time limit (Tlim)) at a load corresponding to 100% individual Pmax, without preliminary warm up. The reproducibility of Tlim when running at 100% (404_+101 s vs 402_+113 s after 1 week) is or cycling above maximal aerobic power (8.19+3.90 vs 7.13_+2.69 rain)~9 has previously been reported.

Test IV: Maximal exerc ise trial fo l lowing (RWU) Subjects performed a warm up exercise at their individual RWU (ie, at an intensity and duration determined in Tests I and II). Following the warm up exercise, the self-determined intermediate pause was observed before perform- ing maximal cycling to exhaustion at 100% Pmax.

Test V: Maximal exerc ise trial fo l lowing warm up below the RWU (RWU-10} This test was identical to Test IV, but the warm up intensity was reduced by 10% compared to the RWU.

Test VI: Maximal 'exerc ise trial fo l lowing warm up above the RWU (RWU+10) This test was identical to Test IV except that warm up intensity was increased by 10% compared to the RWU.

The diminution and the increase of warm up intensity by 10% were to provide an error interval around RWU which was considered as the reference warm up. "rests were scheduled at the same hour of the day for each subject. The field

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warm up was performed in a gymnasium where average ambient temperature and relative humidity were 24.1_+0.9C (range, 23-25) and 60.2+1.2% (range 59-62). Tests II, III, IV, V and VI were performed in a laboratory opened to external air, with similar ambient conditions as the gymnasium.

Statistical analysis All statistical analyses were conducted using the software StatView, version 5.0 (SAS Institute Inc., Cary, NC). Results are presented as means_+SD. A 1-way ANOVA with repeated measures was used to compare means of parameters from Tests III, IV, V and VI. Regressions were determined depending on the gait (tendency) of graphs (linear or polynomial) and the relevant mathematical expression automatically given by the software StatView. Statistical signif- icance was set at the P< 0.05 level of confidence.

Results Warm up variables Power output and durat ion The mean power of the field warm up located during the incremental test (Test II) and serving as the reference warm up (RWU) was 130_+30 W (Table 2). The RWU-10 and RWU+10 intensities were 117.4_+27.1 and 142.8_+34.4 W respectively, with a significant difference between conditions; RWU-10

Are athletes able to self-select..,

warm up intensity Rectal temperature increase (% Pmax) (%HRmax) Ae (C)

FWU 78 -+ 7 0,69 _+ 0.15 RWU-IO 56 + 9 a 72 + 6 a 0.50 _+ 0.12 RWU 62 -+ 10 79 6 0.67 _+ 0.18 RWU+I0 68 + 11 a 84 + 5 a 0.83 0,12 a

a significantly different from RWU (P< 0,05)

Table 1: Relative values of warm up intensity (%Pmax and %HRmax) and rectal temperature increase at the end of warm up (n = 9),

1.1

1.0 6" ~'~ 0,9 o~

0.8

~ 0.7

~ 0.6 E N 0.5

0.4

0.3

56 58 60 62 64 66 68

WU intensity (%Pmax)

Figure 1: Rectal temperature increase (MeanSD) as a function of warm-up (WU) intensity.

v

o) -g

92! 90

85 I f 80 i ~ qr -~-~

75 i i~ j~ J J /~ J~ - 70

65~ ~ , J , - -+~ 56 58 60 62 64 66 68

WU intensity (%Prnax)

Figure 2: Mean+SD Heart rate as a function of warm-up (WU) intensity.

t

(5/9 subjects: ie, 56%), followed in order by RWU-10 (3/9: ie, 33%), RWU+I0 (1/9; ie, 11%) and NWU with significant differences between RWU and NWU {P< 0.01); RWU and RWU+10 (P< 0.01); RWU-10 and NWU (P< 0.01). No subject performed better after NWU compared to RWU-10 and RWU, while three subjects performed better after NWU than RWU+10.

Performance of the maximal trial was related by the following binomial regressions:

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Pmax Hrmax RWU FWU FWU Performance(s) Power Heart rate Duration

(watts) (bpm) (watts) (bpm) (s) NWU RWU-IO RWU RWU+IO

$1 S2 S3 S4 S5 S6 S7 S8 S9 Mean SD

240 195 180 152 900 435 461 546 432 210 192 150 165 720 341 430 345 165 210 191 150 156 780 374 475 515 555 210 190 120 128 1080 197 274 271 253 210 192 150 164 480 349 403 432 405 180 189 90 149 900 361 634 651 442 180 186 90 135 780 308 486 367 285 210 194 120 139 900 302 396 497 312 210 191 120 144 600 257 287 338 308 207 191 130 148 793 324.9 427 .3 440 .2 350.4

18 3 30 13 179 69.3 ab 108.6 121.5 118.1 a

a significantly different from RWU, b significantly different from RWU-10

Table 2: Individual values of maximal exhausting power (Pmax), reference warm up (RWU) power, maximal heart rate (HRmax), field warm up heart rate, field warm up duration and performance during the four trials, with and without warm up; n = 9.

600

500

~, 450

400

350 E ,~ 300

~ 250

2(30

150

100

0 W5~tens,ty (~ Pmax)

Figure 3: Effect of warm-up intensity on performance (Mean SD).

700 , Sl

600 ~ ' ~ . .m. -S2 ,L $3

500 o s4

(D 400 ~ s5 O $6 ~ 300

200 ~ : m rJ $8 r ,

~ $9 100 . . . . 0 10 20 30 40 50 60 70

WU intensity (%Pmax)

Figure 4: The effect of warm-up intensity on individual performance if#m ) .

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- to warm up in tens i ty ,

Y (performance(s))= - 0.145 X2+ 10.363 X + 324.732 (X= WU intensity in % Pmax) (R 2 = 0.95, P< 0.05) (Fig.3) - to re lat ive hear t ra te (%HRmax) ,

Y (performance(s))= ~ 0.108 X 2 + 9.516 X + 324.763 (X= WU HR in % HRmax) (R2= 0.90, P< 0.05)

No significant correlation was found between performance and warm up duration. Analysis gave the following correlation coefficients: RWU-10/WU duration, r= 0.074 (P= 0.8); RWU/WU duration, r= 0.118 (P= 0.77); RWU+10/ WU duration, r= -0.063 (P= 0.88)

DiSCUSsion The originality of this study is the methodological approach based on the self- determined warm up by the subject in the field and replicated in the laboratory. While power was not measured in the FWU trial and thus intensity was based on heart rate, the absence of a significant difference in both rectal temperature increase and heart rate between the free field warm up and the laboratory self- determined warm up suggests that we were able to replicate the self- determined warm up in the laboratory. Warm up intensity was described in terms of the individual maximal exhausting power (Pmax), as we did not measure individual V02max. Nevertheless, the protocol conducted in deter- mining our Pmax is analogous to the one commonly used for maximal aerobic power (MAP) and resulted in a maximum heart rate similar to that predicted from 220-age.

Results showed that, in general, time to fatigue at 100% Pmax was improved following warm up when compared to NWU. It is likely that the improved performance can partly be attributed to the significant rise in rectal temperature during active warm up (Fig. 1). It has been suggested that an increase in temperature may improve performance via a decrease in the resistance of muscles and joints, a speeding of rate-limiting oxidative reactions and/or an increase in oxygen delivery to muscles 16. It is interesting to note however that, while RWU+ 10 produced the greatest increase in rectal temperature, it was not associated with the greatest performance. This suggests that factors in addition to rectal temperature determine the effects of warm up on performance.

The main finding of this study was the regression model linking the performance (time to exhaustion) of subsequent exercise to the intensity of preliminary exercise (warm up). This model shows that the optimal intensity of warming-up for the performance measured in this study (time to fatigue at Pmax) range from 52%-72% Pmax (62_+10% Pmax) if performed for 8 to 18 min. This interval corresponds to what is known as the "aerobic-anaerobic" zone 2 and is close to the ,one suggested by Bishop]7: (Intensity: ~60%-70% VO2peak, duration: 5-10 min, followed by less than 5 min recovery), in structuring warm up for "long-term fatiguing exercise (_>5 min}", as was the case in this study. According to this author, warming-up above these ranges is more likely to deplete muscle glycogen stores and/or increase thermoregulatory strain which are limiting factors for sustained continuous effort. Below these ranges, warming-up may not produce the expected temperature-related and non temperature-related effects. Thus, the results of the present study are con-

32


sistent with previous research 4.1a15, although these authors did not establish a regression equation between warm up intensity and performance.

As not all athletes have access to laboratory testing, it is important to develop field methods to control warm up intensity. The high linear correlation found between warm up intensity and heart rate allows one to suggest that an optimal warm up for "tasks similar to that used in this study (ie, within the range duration 8-18 min.) should induce a heart rate rising to 80%-+6% maximal heart rate (range 73%-85%) Thus, it may be possible to optimise and individualise warm up in the field using modern miniature heart rate monitors to avoid under and over warming-up.

It is important to note that our results only allow us to recommend a range of warm up intensities to optimise performance and that there was some variability in the response. The variability of the warm up effect on performance among the subjects may reflect differences in the sporting background of the subjects, or individual variability of athletes as a result of differences in anthropometric characteristics and/or metabolic responses. This supports our hypothesis that an individualised warm up may be superior to a collectively imposed warm up.

It was observed that no subject performed better after NWU compared to RWU-10 and RWU, and only 3 subjects performed better after NWU compared to RWU+10. This is consistent with previous studies suggesting that warming- up at a moderate intensity is beneficial for performance compared to no warm up 2,4-8,10-12,13-15. Furthermore, it appears that most athletes are able to self- select a warm up that is within -+ 10% of the intensity of their optimal warm up.

In conclusion, some athletes are able to self select the intensity and the duration of their optimal warm up, while for others there is still a need for control. To our knowledge, this is the first study to attempt to establish a mathematical model linking warm up intensity to the performance of a subsequent exercise and to suggest the zone of an optimal warm up. This may help to predict the consequence of warm up on the performance of a subsequent exercise. Further investigations are required to test and refine this mathematical model for other exercise tasks. In addition, while all subjects were familiar with the ergocycte, further research is required to determine if these findings are applicable to elite cyclists.

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are athletes able to self-select their optimal warm up?

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