Effect of high-intensity functional training combined with selenium and zinc co-supplementation on sleep quality, functional capacity and weight loss in overweight and obese people

Participants were randomly divided into two groups. Both groups underwent a 6-week intervention that included a hypocaloric diet and a high-intensity functional training program (HIFT). They differed based on whether they concurrently received one zinc and one selenium supplement or two placebos. The participants in the zinc-selenium co-supplementation group received a supplement containing 25 mg of zinc gluconate and another supplement containing 200 mcg of Se L-selenomethionine. After the baseline measurements, all participants were contacted by the research team's clinical dietician to create a custom-made diet plan. During the interview, participants provided information about their food preferences, allergies, and intolerances. A 24-hour dietary recall was used, with participants reporting their food and beverage intake in the 24-hour period before the interview. The diet plan covered the recommended dietary allowances, and the macronutrients distribution was 50% carbohydrates, 30% protein, and 20% fat. The total calories given to every participant were calculated considering the resting metabolic rate and the caloric expenditure of exercise and physical activity minus 500 calories to follow a hypocaloric diet. The participants of both groups participated in a group-based circuit-type HIFT two times/week and for six weeks. All classes were supervised by an experienced exercise scientist, and the number of participants in each class was small (8 people). Upon arrival at the gym’s facilities, participants performed a ten-minute warm-up using the three-phase RAMP method (Raise, Activate-Mobilize, Potentiate). Following the warm-up, participants completed the main protocol, which included 8-10 cardiometabolic, multi-joint resistance (upper-body; push and pull, lower-body knee-dominant; squat and lunge, hip-dominant; hinge and bridge, and core; plank movements) and neuromotor exercises (exercises aimed to improve balance, agility, coordination, reaction time, and proprioception), for 1-3 rounds. The appropriate exercise technique and baseline starting exercises for each participant were determined in a training session before the start of the intervention. At the end of every round, a rate of perceived exertion (RPE) measurement was conducted using the Borg RPE scale 6-20 to assess the level of exertion participants felt during the HIFT sessions. The mean RPE of each training day was also calculated. Furthermore, mean and maximum heart rates were monitored using Polar heart rate monitors (Polar® H7, Polar Electro Oy®, Kempele, Finland) for one session to measure exercise intensity objectively. The mean heart rate reverse of the participants was maintained higher 60% throughout each session. Progressive overload was achieved by decreasing the rest intervals or increasing the work intervals weekly and by increasing the number of exercises. When any of the exercises started to feel easier, the participants progressed to a harder variation. A 5-minute cool-down, including walking and static stretching exercises, was conducted at the end of the main training. The participants' adherence to the supplements was calculated using the number of remaining tablets at the end of the intervention. Adherence to the exercise program was determined by calculating the number of training days lost using a session attendance sheet. The data were analyzed only if compliance with the exercise program and supplement consumption was equal to or higher than 90%.