Strength & Power Training: Free-weights vs. Machine-based

As some know, I regularly compete in strongman events throughout Colorado. Strongman is unique in that the events are variable; they can be static or explosive. This can complicate training when exposed to a large selection of strength-training equipment. Following is a review of a study that sought to elucidate whether one strength-training implement was superior to another in producing functional outcomes. 

The purpose of this study was to determine how exercise selection, free-weight or machine-based, affected speed/ strength performance during an eight-week training intervention, consisting of: 5 sets of 8-10 repetitions (reps) during the first three weeks, followed by 5 sets of 6-8 reps in the fourth to sixth week, and 5 sets of 4-6 reps in the 7th and 8th weeks. Participants were students of the Institute of Sports Science at Goethe University in Frankfurt, Germany, of which there were 120. They were all male subjects (age: 23.8 ± 2.5 years; body height: 181.0 ± 6.8 cm; body mass: 80.2 ± 8.9 kg), who were divided into three groups. 

The first group completed an eight-week training intervention in which they were subject to two training sessions per week involving the parallel squat bar. The second group completed the same protocol but using the 45-degree leg press. The third group was a control group that did not perform any resistance training. To compare each group, the one-rep maximum, squat jump, countermovement jump, and unilateral isometric force were assessed. Testing was initially done before intervention, during a pre-test that was performed three days after familiarization. The same tests were then performed three days after the last training session in the same order. 

Results were significant (p < 0.001) for an increase in one-rep maximum in both the squat and leg press groups when compared to the control group. The squat group, however, also showed a significant increase (p < 0.001) in the squat jump, starting from a static position of knee flexion, and the countermovement jump, which is initiated from a standing position before going into knee flexion. The takeaway, then, is that the squat and leg press both elicit short-term adaptions in strength, but the squat is possibly superior for increasing jump performance. 

Thus, implications can be made on the training of athletes, especially in the short-term pre-competitive period. Ethically, though, there were some concerns by the researchers regarding their accuracy in measuring data. The specific concern was that the current way of measuring motor tasks with dynamic execution, by comparing values of other contraction types (i.e. isometric contraction), is potentially problematic. I agree with this conclusion, but I also respect the researchers for disclosing their limitations. In doing so, they are perpetuating transparency and ultimately contributing to academic integrity for the beneficence of mankind, as people are more likely to put their trust into a system that is honest.

References:

Wirth, K., Keiner, M., Hartmann, H., Sander, A., & Mickel, C. (2016). Effect of 8 Weeks of Free-Weight and Machine-Based Strength Training on Strength and Power Performance. Journal of Human Kinetics, 53(1), 201–210.