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Mohammadyari S, Saberi Y. Comparison of the Effect of Eight Weeks of CrossFit and High-Intensity Interval Training with Common Physical Fitness Training on Some Factors Related to the Health and Performance of Military Students. J Police Med 2022; 11 (1) : e38
URL: http://jpmed.ir/article-1-1129-en.html
1- Department of Physical Education, Faculty of Basic Sciences, Imam Ali (AS) Officer University, Tehran, Iran , mohammadyari.s@gmail.com
2- Department of Physiology Sport & Corrective Movements, Faculty of Sports Sciences, Urmia University, Urmia, Iran
English Extended Abstract:   (1992 Views)
INTRODUCTION
... [1, 2]. The type of physical fitness appropriate to the nature of work in the armed forces (police, overseas forces, etc.) is of particular importance [3]. For example, in the police force, due to the nature of the job, including the high volume of work and the possibility of conflict, it requires more attention to endurance and muscle strength [4]. In the army's ground forces, due to the high volume of work and exposure to various environments (forest, mountain, plain) and various dangers, they need more attention to endurance, agility and speed. Also, the main body of military forces is in middle age. Therefore, various physical problems and complications can be expected among them [5]. ... [6]. To expand health and specific components of physical fitness, sports activities can be performed regularly and organized [3]. One of the training methods that has attracted the attention of researchers is high-intensity interval training (HIIT) or intense interval training [7]. ... [8]. By studying 50 military men aged 19 to 23 years and comparing the results after eight weeks of continuous and intermittent aerobic exercise, Nikro et al. reported that intermittent exercise improves fat percentage and body mass index and increases oxygen consumption, and they have recommended it to the police. [9]. Also, Ngasa et al. investigated the effect of 6 months of intense interval training on overweight military soldiers, whose results showed an increase in maximal oxygen consumption and a decrease in blood pressure indices [10]. Paine et al.'s study of US soldiers has shown that the CrossFit program and other physical fitness programs present the US military with unique opportunities to improve soldiers' physical fitness levels [11]. ... [12, 13]. Michalski et al. have shown that six weeks of CrossFit training has a significant effect on physical fitness [14]. On the other hand, injuries caused by physical exercises are a major problem among military personnel [15]. ... [16, 17]. Most of the studies have shown the significant effect of this training method compared to common physical fitness exercises [18]. ... [19]. Considering the importance of the level of physical fitness and health components in military personnel, it is necessary to use the best type of exercise to achieve the mentioned goals and to compare Crossfit and intense interval exercises with common physical fitness exercises on selected factors of physical fitness and health.
AIM(S)
The purpose of this study was to compare the effects of modern CrossFit and HIIT exercises with physical fitness exercises on health and functional factors (arterial oxygen saturation, cardiorespiratory fitness, muscular endurance, speed and agility) of military students.
RESEARCH TYPE
The current study is experimental and its design is pre-test-post-test.
RESEARCH SOCIETY, PLACE & TIME
The statistical population included the second-year students of Imam Ali Army Officer University in 2021 in Tehran, Iran.
SAMPLING METHOD AND NUMBER
Based on available and voluntary sampling, 40 people (based on Cochran's formula) with an age range of 19-25 years were selected.
METHOD
After meeting the entry criteria in a semi-experimental design, the subjects were randomly divided into four groups: CrossFit training (10 people), intense interval training or HIIT (10 people), combined training (HIIT + CrossFit, 10 people) and Physical fitness training group (10 people). The exercise group each participated in an eight-week exercise program that consisted of four sessions each week and each session lasted one hour. After selecting the subjects, the selected factors of physical fitness (speed (using the 45-meter speed test), muscular endurance (using the sit-up test), and agility (using the 4×9 test) were performed in the pre-test mode. Also, to measure cardio-respiratory fitness Queen’s staircase test was used and pulse oximetry was used to estimate arterial blood oxygen (SPO2). Queen's stair test for men is such that each subject goes up and down a step with a height of 41.3 cm with a rhythm of 24 steps per minute while listening to a metronome. After three minutes of going up and down with the determined rhythm, the heart rate was measured and the maximum oxygen consumption was obtained. In the following, the subjects of the 4 groups performed their specialized training program for eight weeks, and at the end of the eighth week, the dependent variables of the study, such as the conditions of the pre-test and the post-test, were measured again. The HIIT training program consisted of 15 minutes of warm-up and 30 minutes of specialized training (4 sets of the Rast protocol, which reached 6 sets by the eighth week, with a 4-minute rest between each set) and finally a 10-minute cool-down [20]. Crossfit exercises included three parts: cardio, gymnastic, and body weight and weight movements, which were performed 4 sessions a week as a combination of parts or separately (Table 1) [13]. Common physical exercises also included exercises that were commonly performed at the university by physical fitness trainers four sessions a week.
ETHICAL PERMISSION
The present study was carried out in compliance with all ethical issues in research and maintaining the subjects' information with research number 99.197.3.1786.
STATISTICAL ANALYSIS
After collecting the raw data, inferential statistics methods were used to test the research hypotheses. First, the normality of data distribution was checked with the Shapiro-Wilk test. Correlation t-test was used to examine intra-group differences and one-way analysis of variance with Tukey's post hoc test was used for inter-group effects. SPSS 20 software was used to analyze and perform statistical tests at a significance level of 0.05.
FINDING by TEXT
The results related to the descriptive findings showed that the age group of physical fitness, HIIT, CrossFit and HIIT+ CrossFit included 21.60±1.07, 21.30±1.33, 21.10±1.19 and 22.20±0.91 respectively. The results related to the intragroup comparison using the correlated t-test of the studied variables showed that the maximal oxygen consumption, SPO2, muscle endurance, agility and speed in the HIIT, CrossFit and HIIT+CrossFit groups were significantly different in the post-test compared to the pre-test. In these three groups, maximum oxygen consumption, SPO2, and muscle endurance after the test increased significantly compared to the pre-test, and agility and speed decreased significantly (p<0.05). On the other hand, the intra-group results in the physical fitness group were not significant in any of the studied variables except muscular endurance (p<0.05). Also, by comparing the pre-test and post-test averages of the studied groups, the greatest effect was related to the combined group (HIIT+ CrossFit) (Table 2). The results of inter-group comparison using a one-way analysis of variance test showed that the studied groups had significant differences from each other (p<0.05). Also, the results of Tukey's post hoc test showed that there was a significant difference in maximal oxygen consumption in the groups of physical fitness with CrossFit and physical fitness with HIIT+CrossFit (p=0.001). SPO2, speed, agility and muscular endurance were significantly different between physical fitness groups with HIIT+crossfit (p<0.05) (Table 3).
MAIN COMPARISION to the SIMILAR STUDIES
The findings of the present study are in line with some studies that show that CrossFit exercises can lead to improvement of cardiac and respiratory index [14, 18]. Mcweeny et al. reported that as little as six weeks of CrossFit training can produce significant changes in physical fitness, and significant improvements occur with longer training sessions [14]. ... [21-24]. Azali Alamdari and Armanfar have stated that 8 weeks of intense interval training, compared to resistance training and endurance training, has a significant effect on the cardiorespiratory fitness (maximum oxygen consumption) of young male athletes [24]. Rahmati et al. also stated in their research that six weeks of intense intermittent training caused a significant increase in the maximum oxygen consumption of overweight boys [25]. ... [28-26]. The findings of the present study showed that after eight weeks of exercise interventions (Crossfit, HIIT and common physical fitness exercises), muscle endurance, speed and agility in the intragroup analysis of the HIIT, CrossFit and HIIT+ CrossFit groups had a significant effect compared to the physical fitness group in the post-test. Of course, muscle endurance was also significant in the physical fitness group, but comparing the pre-test and post-test averages of the groups, its effect was low compared to other groups. Also, there was a significant difference between the groups of physical fitness with CrossFit and physical fitness with HIIT+ CrossFit. This finding indicates that if the military forces participate in Crossfit and HIIT exercises at the same time, their muscular endurance, speed and agility can improve better. This finding is consistent with the studies of Michalski et al., Smith et al., as well as the study of Ghanbarzadeh [20, 29, 30]. Michalski et al. have shown male and female participants that CrossFit training increases the level of physical fitness factors [29]. Smith et al have shown in their research that muscular and aerobic endurance increases after CrossFit training [30]. Ghanbarzadeh et al investigated the effect of a period of intense interval training on the physical fitness factors of military forces [20]. The results of this study have shown that intense interval training can improve physical fitness factors [20]. Research has shown that CrossFit training and intense training can increase speed, endurance and muscle strength compared to old training methods [11, 31]. ..... [34-32].
SUGGESTIONS
It is suggested to use up-to-date and attractive exercises such as Crossfit and HIIT instead of common physical fitness exercises. Finally, according to the findings, the present study was the first study that included two exercises, CrossFit and HIIT, simultaneously in the exercise program of the subjects. However, understanding the effects of CrossFit and HIIT combined exercises requires different and more research.
LIMITATIONS
The present study had limitations, among which we can point out the lack of measurement of body fat indices and muscle injuries. Therefore, it is suggested to address this research limitation in future studies.
CONCLUSIONS
Based on the findings of the current research, it seems that Crossfit and intense interval training have a better effect on health indicators (arterial blood oxygen, cardiorespiratory fitness, muscle endurance, speed and muscle agility) compared to common physical fitness exercises the combination of Crossfit exercises and intense interval shows the most effect in military students. Therefore, these exercises can be used as new exercises to increase health and fitness indicators in military centres.
Clinical & Practical Tips in Police Medicine
Considering the importance of health and fitness in the employees and students of police command to establish and maintain security at the community and country level, Crossfit and intense interval exercises can be used to increase fitness and health factors in a shorter period with greater efficiency.
Acknowledgements
This article was taken from the implementation of a research project at Imam Ali Army Officers University. We thank the subjects and all those who helped in the research.
Conflict of Interest
The authors state that there is no conflict of interest in the present study.
Funding Sources
The present study was carried out with the cooperation of the Research Vice-Chancellor of Imam Ali Army Officers University and the researchers themselves.

 
Table 1) Crossfit training protocol
Days of the Week
Saturday Sunday Monday Tuesday Wednesday Thursday Friday
Exercise movements Exercise movements rest Exercise movements Exercise movements rest rest
First M GW - MG W - -
Second MG MGW - W M - -
Third M GW - MG W - -
Fourth MGW W - GW MG - -
the fifth GW M - MG MGW - -
the sixth M GW - W MG - -
the seventh MG W - M GW - -
Eighth M MGW - GW MG - -
M= Aerobic exercise
G= Gymnastic movements (strength stretching movements)
W= Movements with body weight and weights

Table 2) Means of descriptive and physiological variables and comparison of intragroup means (correlated t-test)
Studied groups
Variable Physical fitness group
M±SD))
HIIT group
M±SD))
Crossfit groupM±SD)) Mixed group
M±SD))
pre-test post-test pre-test post-test pre-test post-test pre-test post-test
VO2max (ml/kg/min) 41.50±1.50 75/1±44/42 01/2±40/42 71/1±70/43 86/1±55/43 49/1±95/46 45/2±30/42 13/3±50/46
057/0=p-value 009/0=p-value* 002/0=p-value* 001/0= p-value*
SPO2
(Percent)
73/0±90/96 24/1±00/97 08/1±50/96 42/1±40/97 07/1± 60/96 15/1±70/97 39/1±20/96 80/0±90/98
678/0= p-value 010/0= p-value * 003/0= p-value * 001/0= p-value *

Muscular endurance
36/3±30/37 16/4±60/38 19/3±80/39 34/3±50/41 65/5±20/39 25/5±10/41 85/3±80/38 66/3±90/45
028/0= p-value * 006/0= p-value * 027/0= p-value * 001/0= p-value *
(Number) 55/0±87/9 43/0±69/9 59/0±81/9 49/0±33/9 60/0±60/9 48/0±27/9 53/0± 79/9 46/0±81/8
051/0= p-value 015/0= p-value * 033/0= p-value * 001/0= p-value *
Agility (seconds) 76/0±10/9 74/0±05/9 02/1±03/9 84/0±51/8 93/0±61/9 98/0±93/8 76/0±07/9 51/0±99/7
505/0= p-value 001/0= p-value * 001/0= p-value * 001/0= p-value *


Table 3) The results of one-way analysis of variance and Tukey's post hoc test for the studied groups
Variable Analysis of variance test Tukey's post hoc test
F p-value Comparison of physical fitness group with other groups
HIIT, crossfit and hybrid
Mean
difference
p-value
VO2max 10.48 *0.001 Physical fitness group with HIIT -1.26 0.554
Physical fitness group with Crossfit -4.51 *0.001
Physical fitness group with HIIT+ Crossfit -4.06 *0.001
SpO2 4.693 *0.007 Physical fitness group with HIIT -0.40 0.877
Physical fitness group with Crossfit -0.70 0.563
Physical fitness group with HIIT+ Crossfit -1.90 *0.006
Speed 3.685 *0.02 Physical fitness group with HIIT 0.54 0.434
Physical fitness group with Crossfit 0.126 0.984
Physical fitness group with HIIT+ Crossfit 1.06 *0.024
Agility 5.84 *0.002 Physical fitness group with HIIT 0.35 0.347
Physical fitness group with Crossfit 0.41 0.211
Physical fitness group with HIIT+ Crossfit 0.87 *0.001
Muscular endurance 5.29 *0.004 Physical fitness group with HIIT -2.90 0.417
Physical fitness group with Crossfit -2.50 0.544
Physical fitness group with HIIT+ Crossfit -7.30 *0.002
Article number: e38
Full-Text [PDF 741 kb]   (1757 Downloads)    
Article Type: Original Research | Subject: Police Health
Received: 2022/09/13 | Accepted: 2022/10/25 | Published: 2022/12/4

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