Is Inertial Training More Effective Than Conventional Strength Training?

A group of 42 young men attended an initial recruitment meeting and all 30 men agreed to participate in the study. The study finally included twenty-six men (mean ± standard deviation: age, 20.4 ± 1.18 years; body mass, 81.0 ± 11.4 kg; height, 184 ± 6.28 cm). The participants were physical education students, but all of them were untrained. The participants were randomly allocated into two groups: inertial training group: IT (n = 13) and a body building training group BBT (n = 13) with the chit method - a simple method of generating random sequence. Both groups participated in 6 weeks of training, IT performed inertial training, BBT performed body building training. All participants were asked to maintain their current level of physical activity and diet throughout the duration of the study. However, we did not control their lifestyle.

Before and after the training muscle strength under different conditions were tested. Moreover, jumping ability, body composition, circumferences of the limbs were evaluated. Each time measurements were performed in five separate days.

1RM

Measurement of 1RM and estimation of training loads. Before training participants were learned techniques of exercise in body building and inertial conditions in two a familiarization sessions. Then, 1RM was determined for the unilateral elbow flexion in standing position using dumbbells and for the unilateral leg extension in sitting position for all participants. 1RM was determined using traditional weights. Next the participants performed 1 set of unilateral flexion in the elbow joint (12 repetitions) and 1 set of unilateral extension in the knee joint with a load of 70% 1RM. During each set, the time of its performance was measured - the participants tried to complete this set in the shortest possible time. Two days later, the training load for inertial training was determined using Cyklotren (Inerion, Poland). Each participant performed several sets of exercises with different loads. The load was increased/decreased so that the performance time of 12 repetitions (as fast as possible) was the same (with an accuracy of 0.5 s) as in the set time with the 70% 1RM using traditional weights. If in three sets between which 5-minute breaks were applied, it was not possible to determine the load in inertial exercises, the test was repeated on the next day. The range of motion and the body position of the participant during load determination were identical to those in the body-building conditions.

Measurement of maximal force under inertial conditions. The maximal force under inertial conditions (IFmax) was measured using Cyklotren inertial device (Inerion, Poland). Participant position during IFmax measurements both for elbow flexors and knee extensors was the same as during 1RM test. Briefly, after a warm-up, each participant performed a 10-s maximal strength test (elbow flexion and knee extension) the right and left arms separately, with a 2-minute break between measurements. Estimated training loads were used during testing. The range of motion for elbow flexors was approximately 130 degrees and for knee extensors approximately 80 degrees. Cyklotren device displayed on the screen and recorded force level for each repetition, the highest value of force (N) was used for future analysis.