Effects of circuit hydraulic weight-interval training on body fat, muscle mass and progression of resistance in pre- and postmenopausal women

The present study was carried out at the Sports Centre for Women - JollyFit in Wroclaw (Poland). Participants recruited for the project were women aged between 35 – 69 years old from an urban population, who for at least a year had not taken part in any type of resistance or circuit workout and declared their regular involvement in the study training sessions. At recruitment, the subjects were divided into pre- and postmenopausal groups. After enrolling for the study, the participants of both: pre- and postmenopausal groups, were randomly assigned to either training or a control group. All persons consented in writing to take part in the study. The research project was approved by the local Research Ethics Committee. The participants declared that they would not change their diet throughout the study period of 18 weeks or attend any other physical activity exceeding their regular, daily level of activity. Before the first exercise session, there was organised a training, regarding the appropriate position on each hydraulic machine and the proper manner of exercise. During each subsequent session, a personal trainer supervised the exercise and corrected the body position. Each participant had their body height (cm), body mass (kg), the circumferences of waist (cm), hips (cm), right thigh (cm), and right upper arm (cm) measured. The indexes of BMI and WHR were calculated. Body fat (%) and muscle mass (kg) were estimated, applying a bioimpedance method with the usage of TANITA BC-418MA analyser (Japan) with GMON software - version 3.1.8. Muscle performance was determined by the maximum number of repetitions an exercise on each of eight hydraulic machines used in the study. In both experimental age groups the measurements were made before the series of exercise, then after 6, 12 and 18 weeks of training. At each stage of the study, the effects of exercises were discussed with the participants and another training aim was established. In the control group, the measurement were done before and after the intervention. Training lasted 18 weeks and the subjects performed three workouts per week. Each participant took part in a total of 54 training sessions during the study. Exercises were conducted in two age groups: pre- and postmenopausal, under a constant supervision of a qualified trainer. The study included women who met the criterion of participation in the classes 3 times a week. Session attendance checklists were checked by the trainer to monitor adherence to the intervention. The training protocol consisted of three full workout circuits on the hydraulic gym machines, based on controlled resistance which addressed main muscle groups. The pressure ranges on each machine was set a level of three bars. The exercises were done in a continuous manner, at a maximum effort on the machines, with repeated intervals of 40 seconds, between which there were 40-second-long periods of active rest on the transition stations. The participants were instructed to do as many repetitions as possible on every hydraulic machine. A single training session lasted 32-34 minutes with additional time for stretching. One circuit consisted of eight stations of hydraulic machines and the same number of transition stations set alternately. After each circuit there was a heart rate measurement lasting 10 seconds. A half of the first circuit was treated as a warm-up and the work done was at the level of around 50% of maximum heart rate. Then, after the fourth machine, acceleration took place and at this stage the work was at 60-70% of maximum heart rate. Such a pace was kept until the second half of the third circuit, during which the intensity of exercise and heart rate decreased. After last circuit completion, there was a standard procedure of whole body stretching. In the study following machines with hydraulic resistance were used: pulldown/shoulder press; adductor/abductor; chest press/rowing; hip extension 1 and hip extension 2 ; back extension/flexion (training abdominal and back muscles); butterfly/butterfly reverse, and squat.