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The effects of two different endurance training programs performed in hot environment on body temperature and some physiological parameters.


In resting condition, organism produces approximately 1.5 kcal/min. energy. Especially during exercise with the increase in heat production 15-40% of chemical energy converted into mechanical energy, the rest of the energy produced converted into heat that is required to remove from body to maintain heat balance (H.A. Devries, 1986; E.L. Fox, 1988).

Heat dissipation mechanism in body, is unable to cope with the metabolic heat production starts to accumulate and cause on increase in body temperature (S.S. Cheung et al., 2000). In normal weather conditions, players can use 80% of energy reserves when exercising in hot environment, exhaustion occurs before it reached that level or they perform less work (T. Lav, 1995).

Exercise increases the metabolic heat generation, this increment can be 30 times more in heavy exercise. One important factor affecting body heat loss is the ratio of moisture in the air. In other words, unlike exercising the hot-dry weather the removal of heat is more important in hot-humid air.

Exercises in hot environments have different effects depending on type, duration and intensity of exercise. In such case, organism makes some physiological regulation to resume normal functions of the body. Increased heat during exercise done with 70% of maxV[O.sub.2] removed from body with conduction and convection (15%), radiation (5%) and evaporation (80%) (J.H. Wilmore, 1994). Complete acclimatization of humanbeing to hot weather occurs in 8-12 weeks. Adaptation to heat reduces symptoms such as heat causes dizziness, fatigue, fainting and also body prepares itself for a comfortable working environment. Although different results obtained from different studies, common opinion of the researches about acclimatization to heat and to heat changes is initial adaptation can be observed first 4-14 days and complete adaptation occurs between 8-12 weeks (D. Wendt et al., 2007). The aim of the study was to determine and compare the effects of two different training programs performed in hot environment on body temperature and some physiological parameters.

Material and Methods

Totally 25 voluntarily university students who were from Ataturk University School of Physical Education and Sports, participated in this study. They were divided into 2 groups as Interval Running Group (IRG) (n=12) and Continuous Running Group (CRG) (n=12). Physical and physiological characteristics of subjects showed in Table 3. Subjects trained in average 30.76 [+ or -] 1.71[degrees]C weather temperature and 57.92 [+ or -] 5.80% humidity ratio environment conditions. Measurements were done before and after the training program and some parameters like body temperature (BT), body fluid percentage (Bf %) and basal metabolic rate (BMR) measured before and after the each training session to observe adaptation. The following test were done during study.

Body Composition

Body weight (BW), body mass index (BMI), body fat percent (BF%), body fluid percent (Bf%) and basal metabolic rate (BMR) values of the subjects were tested by Bio-Impedance Analysis method with Tanita-TBF 300.

MaxV[O.sub.2] scores of the subjects were determined by 20 m Shuttle Run Test.

Body temperature of the subjects was measured with Braun IRT-4520 (Thermoscan) from inside of ear before and after the each training session.

During 8 weeks the subjects participated in either Interval Running Training (IRT) or Continuous Running Training (CRT) programs. The intensity of the training sessions were determined according to target heart rate of subjects that is calculated by Karvenon method. 5-10 min. before and after each session separated as warm-up and cool-down part of the session. Following training programs applied to the subjects during 8 weeks.

Table 2. shows the duration and intensity of interval running for one set. Program planned as first 2 weeks 1 set, 3 -6 weeks 2 sets and 7-8 weeks 3 sets.

Statistical Analysis The effect of endurance training on body weight (BW), body mass index (BMI), body fluid percent (Bf %), body fat percent (BF %), basal metabolic rate (BMR), body temperature (BT) and maximal aerobic capacity (maxV[O.sub.2]) were tested before and after training by 2 way ANOVA using General Linear Method (GLM) procedure (SPSS for windows 11.5.0 Chicago, IL, USA). Statistical significant was decelerated at p<0.05.


Table 4 showed that at the end of the 8 weeks, maxV[O.sub.2] scores of both groups significantly increased (p<0.001). Body temperature and loss of fluid was significantly higher in CRG than that of IRG. Also except BMI, significant changes were observed in BW, BF %, and BMR scores of both groups (p<0. 01).


In this study, it was aimed that which one of two endurance training methods was more effective to develop maxV[O.sub.2] and also in adaptation to hot environment.

Individuals who do endurance training, need less time for full adaptation to heat. The possible reason for this rising in core temperature during training. Thermoregulatory mechanism of the athletes should be strong. Activities carried out at ambient temperature at a level that can be tolerated by the body, through, if the body's thermoregulatory system is not normal, poor results are inevitable (K.B. Pandolf, 1998).

D.E. Rae et al. have done in their study of 35.627 bikes and marathoners, have followed the contest period and only 5 of the athletes were hospitalized with heat shock diagnosis were determined. The standard calculations existing environmental conditions and exercise rates, athletes none of that is difficult due to heatstroke and had a need while hospital admission during the riders' rectal temperature was 42.0[degrees]C and 41.2[degrees]C, marathoners' rectal temperature of 41.8[degrees]C were determined and in these cases death has resulted. As a result, it can be said that increased rectal temperature and disruption in body's cooling mechanism caused these deaths.

According to the results of the study, body temperature of the subjects showed the changes in IRG and CRG due to difference in load. When average body temperatures were analyzed at the beginning of trainings, although CRG had lower body temperature than that of IRG, they reached higher body temperature through the end of the trainings (table 4).

Results also indicated that while resting body temperature of CRG gradually decreased through out the training program, body temperature of IRG has not seen an extreme increase. That occurred as a result the training seems to be an adaptation to the heat environment. However, both endurance training methods resulted in a significant increase in body temperature.

J.G. Morris et al. (2005) compared the effects of the endurance exercise in hot environment at different times of the day (morning and afternoon). Compared to afternoon exercises to morning exercises, fatigue more quickly occurred in afternoon exercise. The reason of that was connected to initial body temperature of the subjects.

Maintaining of homeostasis, human body required to keep body temperature in a certain level (36.9 [+ or- ] 0.5[degrees]C) (N. Altareki et al, 2009). This thermal regulation is much more important and difficult during exercise. There are many factors which affect the thermal regulation, some of them are maxV[O.sub.2], body weight, body mass index, body fat %, body fluid % and basal metabolic rate. In this study, BMI, all parameters were affected from exercise but differences in training methods did nor show different effect against the above mentioned parameters (table 4).

One of the most important differences between individuals is BF %. The amount of fat is extremely effective in heat transfer by conduction and blood flow (M. Tung, 2004).

At the end of the study both training methods effected, BW, BMI, BF%, Bf %, and BMR (table 4). Especially body fluid percent (Bf%) is very important for body. Normal Bf % range is known as 55-66%.

D.A. Judelson et al. indicated that the athletes who started the endurance exercise with good body fluid level has better hormonal regulation in their body than the athletes with less body fluid level.

Consequently, the results showed that IRT was more beneficial in adaptation heat environment both training methods caused significant increase in maxV[O.sub.2] but body temperature further increased during CRT. Starting the exercise with low body temperature can facilitate adaptation to heat environment. Increment in body temperature may cause early exhaustion especially in CRT. Moreover from forth week of the training program, significant increases were not observed between pre and post-test scores of IRG.

In this study, except BMI, all parameters were affected from exercise but the differences in training methods showed different effect on above mentioned parameters.


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Cicioglu Ibrahim (1), Kiyici Fatih (2)

(1) Gazi Univ. School of P.E. Ankara / TURKEY

(2) Ataturk Univ. School of P.E. Ankara / TURKEY

Tablo 1. Descriptive Statistics of Interval Running (IRG)
and Continuous Running Groups (CRG)

                           IRG                   CRG
               n       X [+ or -] SS         X [+ or -] SS

Age (yrs)          24,27 [+ or -] 2,71   22,73 [+ or -] 3,51
Height (cm)   24    1,75 [+ or -] ,06     1,73 [+ or -] ,06

Table. 2. Duration and Intensity of Interval Running Training (IRT)

           Maximal   (Target HR) beat/min
Running    Running
Distance   Times       60%   70%   80%

250 m       40 sn       56    52    48
400 m       64 sn       90    83    77
650 m      114 sn      160   148   137
900 m      165 sn      231   215   198

Continuous Running Training (CRT) In this method the subjects
trained with 80-70% with Target HR from 25 to 60 min and 3
times per week during 8 weeks (Table. 3)

Table. 3. Duration and Intensity of Continuous Running
Training (CRT)

            Duration    Yogunluk
             (min.)    (Target HR)     Day / Week

1.   Week    25 min        %50       3 days / week
2.   Week    30 min        %50       3 days / week
3.   Week    35 min        %60       3 days / week
4.   Week    40 min        %60       3 days / week
5.   Week    45 min        %60       3 days / week
6.   Week    50 min        %70       3 days / week
7.   Week    55 min        %70       3 days / week
8.   Week    60 min        %70       3 days / week

Table. 4. The Effect of Type and Duration of Training in Hot
Environment on Physiological Parameters, Body Temperature
and MaxV[O.sub.2] Levels of Subjects

Type of                            BMI
Exercise    Time    BW (kg)   (kg/[m.sup.2])   BF (%)   Bf (%)

IRG         Pre-    74.5          24.15        15.23    62.64

            Post-   74.0          23.94        14.66    62.01

CRG         Pre-    71.9          24.14        14.46    63.00

            Post-   71.2          23.88        13.92    62.46

SEM                  0.6           0.12         0.17     0.12



E                   0.0001         0.74        0.0001   0.001
t                   0.28           0.06        0.001    0.0001
T                   1.00           1.00        1.00     1.00
E x t               0.91           0.84        0.91     0.75
E x T               1.00           1.00        1.00     1.00
t x T               1.00           1.00        1.00     1.00
E x t x T           1.00           1.00        1.00     1.00


Type of                              BT
Exercise    Time    BMR (kcal)   ([degrees]C)   MaxV[O.sub.2]

IRG         Pre-       1752         36.05           32.45

            Post-      1746         36.47           45.93

CRG         Pre-       1812         35.85           31.93

            Post-      1806         36.47           45.63

SEM                     9            0.03



E                     0.0001        0.0001           --
t                      0.54         0.0001         0.0001
T                      1.00         0.001          0.75
E x t                  0.99         0.0001           --
E x T                  1.00         0.001            --
t x T                  1.00         0.001          0.93
E x t x T              1.00         0.001            --

E = Exercise, t = Time, T = Tye of Training, Ext = Exercise and
Time, ExT = Egzersiz and Training, ExtxT = ExercisexTimexTrainin
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Author:Ibrahim, Cicioglu; Fatih, Kiyici
Publication:Ovidius University Annals, Series Physical Education and Sport/Science, Movement and Health
Article Type:Report
Geographic Code:7TURK
Date:Jun 1, 2010
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