The Effects of Running Compared with Functional High-Intensity Interval Training on Body Composition and Aerobic Fitness in Female University Students

igh-intensity interval running (HIIT-R) and high-intensity functional training (HIFT) are two forms of HIIT exercise that are commonly used. The purpose of this study was to determine the effects of HIFT on aerobic capacity and body composition when compared to HIIT-R in females. Twenty healthy, untrained female university students (age 20.5 0.7 year) were randomly assigned to a 12-week HIIT-R or HIFT intervention. The HIIT-R group involved a 30 s maximal shuttle run with a 30 s recovery period, whereas the HIFT involved multiple functional exercises with a 2:1 work-active recovery ratio. Body composition, VO 2max, and muscle performance were measured before and post intervention. As a result, HIIT-R and HIIT-F stimulated similar improvements in VO 2max (17.1% 5.6% and 12.7% 6.7%, respectively,p> 0.05). Only the HIIT-F group revealed signi cant improvements in muscle performance (sit-ups, 16.5% 3.1%, standing broad jump 5.1% 2.2%,p< 0.05).

functional exercises with a 2:1 work-active recovery ratio. Body composition, VO 2max, and muscle performance were measured before and post intervention. As a result, HIIT-R and HIIT-F stimulated similar improvements in VO 2max (17.1% 5.6% and 12.7% 6.7%, respectively,p> 0.05). Only the HIIT-F group revealed signi cant improvements in muscle performance (sit-ups, 16.5% 3.1%, standing broad jump 5.1% 2.2%,p< 0.05). Body fat percentage decreased (17.1% 7.4% and 12.6% 5.1%, respectively, p< 0.05) in both HIIT-R and HIIT-F with no between-group differences. We concluded that HIFT was equally effective in promoting body composition and aerobic tness compared to HIIT-R. HIFT resulted in improved muscle performance, whereas the HIIT-R protocol demonstrated no gains. Keywords: high-intensity interval training; high-intensity functional training; body composition; aerobic tness; muscle performance 1. Introduction Regular physical activity (PA) is bene cial for health [1–3]. Despite the well docu- mented bene ts of moderate- to vigorous-intensity PA, 31% of adults worldwide do not engage in suf cient PA for health bene ts as recommended by the World Health Organi- zation (WHO) and the American College of Sports Medicine (ACSM) [4–6]. Frequently reported barriers to physical activity are physical exertion, time, and nancial expen- diture [7,8]. Thus, compared to traditional continuous training, which is characterized by long-duration, continuous aerobic exercises, and moderate-intensities, high-intensity interval training (HIIT) appears to be an ef cient pathway to enhance PA and improve health [9]. HIIT involves repeated bouts of high-intensity exercises separated by a recovery using low-intensity activities or inactivity [10]. Recent studies had indicated that HIIT has a similar, or even greater positive, effect on physical tness, especially on body composition and cardiorespiratory health [11–14]. From a time/bene t perspective, HIIT appears to help physically inactive individuals overcome a major time and participation barrier to maintaining a healthier lifestyle [15]. Int. J. Environ. Res. Public Health2021,18, 11312.

Int. J. Environ. Res. Public Health2021,18, 11312 2 of 14 Originally, HIIT was used to improve the performance of endurance athletes [16]. Cycling, running, and rowing are traditional exercise modalities that adopted the use of HIIT protocols, while for individuals who perform exercise for health and recreation, these traditional modalities seem boring and do not engage individuals because of the repetitive nature of the exercise combined with repetition. This is considered as a negative impact for maintaining regular exercise and has been cited as “lack of enjoyment” when investigating barriers to exercise [17]. The intrinsic factors of participants are also important when considering exercise adherence [18,19]. Several studies have revealed that adherence is affected by exercise intensity, especially among inactive individuals [20,21]. High-intensity functional training (HIFT) has become a relatively popular training modality in recent years and is an alternative to traditional aerobic activities. The HIFT protocol consists of a variety of functional movements that are executed at a high inten- sity [22,23]). Recently, several investigators have studied the effects of HIFT on physical tness promotion. After engaging in HIFT protocols, participants show signi cant improve- ments in cardiorespiratory tness [24,25] and body composition [25,26]. Providing similar or greater health promotions compared to moderate-intensity continuous training, HIFT demonstrates further improvements in muscle tness [27,28]. Additionally, participants perceive this type of activity to be more enjoyable when engaging in HIFT compared to those individuals performing traditional HIIT [29,30]. Moreover, most HIFT protocols are executed using the participant's own body weight, allowing the participant to control the exercise intensity. This helps to improve exercise adherence [7,19,20]. Although studies have shown that HIFT has similar or superior bene ts for physical tness compared to moderate-intensity continuous training and have indicated more enjoyment compared to HIIT, the question remains as to whether HIFT is as ef cient as HIIT for improving health-related tness. While HIFT is not synonymous with HIIT, they share an important conceptual com- monality in the modality of both being of a high intensity. The current study was under- taken to clarify how a functional exercise based on HIIT would improve

to HIIT, the question remains as to whether HIFT is as ef cient as HIIT for improving health-related tness. While HIFT is not synonymous with HIIT, they share an important conceptual com- monality in the modality of both being of a high intensity. The current study was under- taken to clarify how a functional exercise based on HIIT would improve tness parameters such as fat mass, blood pressure, VO2max, and muscle endurance following a 12-week intervention compared to changes achieved using a running-based HIIT. The purpose of this study was to investigate the effects of different kinds of training on tness parameters in untrained female university students. It was hypothesized that (a) aerobic tness would be increased in both the HIIT-F and HIIT-R groups; (b) that fat mass would be decreased in both the HIIT-F and HIIT-R groups; and (c) that muscular strength and endurance would be improved in the HIIT-F group. 2. Materials and Methods 2.1. Participants Twenty untrained healthy females who were physical inactive volunteered to partic- ipate the study. Participants who did not exercise for more than 2 h weekly for at least 12 months were considered as physically inactive [31]. All of the participants were in their second year of a non-physical education-related degree at Ningbo University. Similar self-reported menstrual cycles were required, ensuring the simultaneity of testing and training. Interventions were suspended for 1 week during menstruation, and the normal menstruation period lasted for 3 to 10 days [32,33]. A randomized controlled research design was utilized, and participants were randomly assigned into a running-based HIIT (HIIT-R) (n= 10) or a functional training-based HIIT (HIIT-F) (n= 10). The participants were nonsmokers and were instructed to maintain their normal dietary intake and lifestyle habits (sleep, sit, and physical activity) throughout the intervention. Nutritional supplements and intense exercise beyond their usual exercise habits were forbidden during the intervention period [31]. All of the participants were fully familiarized with the test procedures and data collection methods prior to the intervention. Written informed consent was provided

physical activity) throughout the intervention. Nutritional supplements and intense exercise beyond their usual exercise habits were forbidden during the intervention period [31]. All of the participants were fully familiarized with the test procedures and data collection methods prior to the intervention. Written informed consent was provided

Int. J. Environ. Res. Public Health2021,18, 11312 3 of 14 by all participants. The study was approved by the Ningbo University ethics committee. The characteristics of the participants at baseline are detailed in Table. Table 1.Baseline characteristics of HIIT-R and HIIT-F group. Parameter HIIT-R Group ( n= 10) HIIT-F Group (n= 10) p-Value Age (yrs) 20.7 0.6 20.2 0.7 p= 0.14 Height (m) 161.1 3.1 160.7 2.8 p= 0.76 Weight (kg) 56.6 6.7 57.8 6.7 p= 0.69 Lean muscle mass (kg) 36.5 1.7 36.0 2.1 p= 0.53 BMI (kg/m 2 ) 21.9 3.1 22.4 2.2 p= 0.70 WHR 0.80 0.0 0.80 0.0 p= 0.79 Body fat (%) 31.6 4.1 32.3 3.6 p= 0.71 HR resting (bpm) 70.8 13.9 72.5 11.2 p= 0.77 HR max (bpm) 188.2 9.7 189.1 10.4 p= 0.18 VO2max (mL/kg/min) 31.3 7.0 32.8 5.4 p= 0.61 Notes: BMI, body mass index; bpm, beats per minute, HIIT-F, functional exercise-based high-intensity interval training; HIIT-R, running-based high-intensity interval training; HR resting, resting heart rate; HR max, maximal heart rate; VO2max, maximal oxygen uptake; WHR, waist to hip ratio; yrs, years old. 2.2. Procedures A randomized controlled trial was used in this study. Each participant completed twelve weeks of 36 sessions of HIIT-R or HIIT-F intervention (three sessions per week) comprising a total of 19 min per session (10 min warm-up, 4 min work-out, and 5 min cool-down). All sessions were conducted and monitored at the same indoor stadium and at the same time of day between 9:00–10:00 a.m. Heart rates (HR) were collected with an activity wristband (Mi Smart Band 5, Xiaomi, Beijing, China) during each session to ensure that the required high intensity was achieved. The reliability and validity of the heart rate index and distance index were reported in a previous study [34]. The activity wristband was required to be worn tightly on the participant's wrist. The HR index was measured based on changes in the light transmittance caused by blood ow density using optical sensing technology, and the distance index was measured by a triaxial acceleration sensor. Two measurement time points (pre- and post-intervention) were included. The

in a previous study [34]. The activity wristband was required to be worn tightly on the participant's wrist. The HR index was measured based on changes in the light transmittance caused by blood ow density using optical sensing technology, and the distance index was measured by a triaxial acceleration sensor. Two measurement time points (pre- and post-intervention) were included. The participants were instructed to abstain from drugs, alcohol, and intense exercise two days prior to the baseline and post-intervention measurements. On the rst measurement day, the participants presented themselves at 8:00 a.m. and underwent a body composition analysis, physical, and physiology measures as well as resting heart rate (HRresting) and blood pressure (BP) measurements under standardized conditions. The aerobic tness assessment was conducted using a 12 min running test, which was completed on two days, with 24 h observed between each test. The rst running test was scheduled on the rst measurement day following the completion of all of the other tests, and the second trial was 24 h later. The average of the two data sets was used to assess aerobic tness. After resting for a week [35], both groups began the training intervention. Post-intervention measurements were performed using the same methodologies as at baseline and were undertaken two days following all of the training sessions [11]. During the intervention period, additional exercises including habitual training were suspended. 2.3. Physical, Physiological and Body Composition Assessment Participants were instructed to arrive at the laboratory 9:00 a.m. after a normal breakfast. Before the measurements were taken, participants were asked to empty their bladder to minimize measurement errors caused by “electrically silent” [36].Under the guidance of two skilled operators and while wearing normal PE clothing, the participants stood on a bioelectrical impedance analysis device (BIA) (MC-180, TANITA CO., Dongguan, China) and data were presented from the device's associated software and included height, weight, waist and hip circumference, lean muscle mass, and body fat percentage. Body mass index

analysis device (BIA) (MC-180, TANITA CO., Dongguan, China) and data were presented from the device's associated software and included height, weight, waist and hip circumference, lean muscle mass, and body fat percentage. Body mass index

Int. J. Environ. Res. Public Health2021,18, 11312 4 of 14 (BMI) was obtained by dividing weight (kg) by height (m) squared. Waist-to-hip ratio (WHR) was obtained by dividing waist (cm) by hip (cm). Blood pressure and resting HR were measured using an automatic upper arm blood pressure monitor (HEM-1000, Omron, Dalian, China). The average of the two data sets was used for analysis. 2.4. Aerobic Fitness Test The most reliable and effective way to measure aerobic capacity is to record each individual subject's VO2max [37]. Although maximal-effort tests are commonly used to measure VO2max, for untrained participants, submaximal exercises can be used as a reliable measure to estimate this value. Cooper's 12 min running test was used to assess aerobic tness in this study. All of the participants completed two trials of the running test separated by 24 h of rest. After a 5 min warm up, the participants were required to wear an activity wristband (Mi Smart Band 5, Xiaomi, China) and commenced running on a standard 400-metre running track. Subjects were instructed to run as many laps as possible on a standard outdoor track during the 12 min test period. All of the participants were encouraged verbally and were instructed to focus on their own pace throughout the test. The experimenter verbally provided the elapsed time at 3, 6, and 9 min. At the end of the 12 min period, the experimenter called “stop”. All of the participants ceased running and stood still, until the distance achieved, and maximal heart rate (HRmax) were recorded. The HRmax displayed on the activity wristband was recorded immediately upon the cessation of exercise, and the higher value of the two trials was used for analysis. The total distance run was determined by measures obtained from the activity band. An estimated VO2max was calculated using Cooper's standardized equation [38]. The calculated VO2max was highly correlated with the laboratory-determined one and had acceptable reliability and validity (r = 0.897) [38]. The average of the two data sets was used to determine the VO2max. 2.5. Muscle Performance Test Muscle performance was assessed using a eld-based

measures obtained from the activity band. An estimated VO2max was calculated using Cooper's standardized equation [38]. The calculated VO2max was highly correlated with the laboratory-determined one and had acceptable reliability and validity (r = 0.897) [38]. The average of the two data sets was used to determine the VO2max. 2.5. Muscle Performance Test Muscle performance was assessed using a eld-based muscle tness test battery. Timed sit-ups, push-ups with exed knee (modi ed for females), and standing broad jump were recommended by previous studies to assess muscle performance [26,39–41]. All of the participants were instructed to perform the tests under supervision, and the data were recorded by the same experimenter. To assess abdominal muscular performance, the participants were asked to perform as many sit-ups as possible during a one-minute test period. The number of sit-ups that were completed correctly were recorded. A sit-up that met the following criteria was recorded: the participant lay supine on the mat with their hands crossed behind their head, elbows pointed straight forward, and knees bent at 90 degrees. The ankles were rmly held by the experimenter. During the execution of the test, the participants sat up with their heads clasped in their hands, and then their elbows touched or went over the knees, and the participant went back with their shoulders touching the mat [42]. To assess upper body strength and endurance, the exed knee push-up option was used as a gender modi cation [39]. A correct exed knee push-up met the following criteria: participants knelt on the mat with their knees bent to the mat with their arms propped on the mat slightly wider than the shoulders. When the test began, the participants were instructed to lower their body by bending their arms until their elbows were bent at a 90-degree angle and their chest was placed within 2 inches of the mat, subjects then pushed up to the starting position [43,44]. The number of correctly completed push-ups during a one-minute test period was recorded as upper body strength and endurance. Finally, the standing broad jump test was used to assess the muscle power

their elbows were bent at a 90-degree angle and their chest was placed within 2 inches of the mat, subjects then pushed up to the starting position [43,44]. The number of correctly completed push-ups during a one-minute test period was recorded as upper body strength and endurance. Finally, the standing broad jump test was used to assess the muscle power of the lower limbs. The participants wore sneakers and stood behind the starting line with their feet placed naturally at a shoulder width apart. When testing began, the participants were instructed to bend the knees, swing the arms, and jump with both feet at the same time [45]. The jumping distance measured in centimeters was recorded, and the best of

Int. J. Environ. Res. Public Health2021,18, 11312 5 of 14 three jumps was used to determine lower limb performance. All scores were compared for statistical analysis. 2.6. Intervention Exercise interventions commenced one week after the last measurement day. Both the HIIT-R and HIIT-F interventions were conducted three days per week on Mondays, Wednesdays, and Saturdays for twelve weeks. If the participants were unable to attend a scheduled exercise day, the exercise was performed on the next day and was monitored by the same researcher. Participants in the HIIT-R group were required to complete 144 repetitions of maximal shuttle running for a total exercise time of 72 min. Each bout included a 30 s maximal shuttle run between cones placed 20 m apart with a 30 s recovery period between runs. The validity and reliability of 40 m maximal shuttle run as a measure of anaerobic performance has been reported previously [46]. The participants completed 4 bouts per session over three sessions per week. Prior to the intervention, a familiarization trial was provided to acquaint the participants with the training procedure. Running and recovery times were recorded manually using a digital stopwatch by the same experimenter. Participants were encouraged to run at their individual maximal speed for each bout. Participants in the HIIT-F group performed multiple functional exercises using their own body weight based on Tabata training [47]. According to a recent study [48], eight movements were implemented in each session (Table). Participants were motivated to complete as many repetitions of a given movement as possible over 20 s followed by a 10 s recovery in the form of low intensity stepping. There was no rest period between each movement. The total training time for each session was 4 min. Table 2.Details of the functional high-intensity interval training intervention. Duration Frequency Exercises Exercise Bout/ Recovery Duration 12 weeks 3 sessions/week Jumping Jacks 20 s Stepping 10 s High knees 20 s Stepping 10 s Side to side squat 20 s Stepping 10 s Mountain climbers 20 s Stepping 10 s Forearm plank to high plank 20 s Stepping 10 s Burpees

This research compares HIIT-R and HIFT effects on fitness in female university students.