Exercise selection is just one of the many variables involved in planning a training routine. That being said, exercise selection may have bigger consequences than one might think. There are clear differences between an exercise using free weights and the same movement on a machine. Free weights require stabilization of the weight in several planes, whereas machines provide guided resistance along a fixed plane. In addition, the required stabilization may affect muscle activation and force generation. For example, muscle activation is higher while using dumbbells for chest press, yet the actual muscle force generated is around 17% less when using dumbbells compared with using a barbell. This difference in muscle activity and force generation could lead to differences in recovery.
Researchers from the University of Brazil assigned men to one of three groups: Smith machine bench press, barbell bench press, and dumbbell bench press. Muscle swelling, peak muscle force, and soreness were measured before, immediately after, and then at 24, 48, 72, and 96 hours following exercise.
The results differed by muscle group. Muscle soreness and peak force recovery of the pecs and front delts required 48 to 72 hours to dissipate for all groups. The triceps followed the same pattern of soreness and force recovery for Smith machine and barbell bench press, with barbell being slightly slower to recover. The dumbbell bench-press group, however, did not experience any soreness of the triceps. Finally, the barbell bench press was perceived as the most taxing of the three exercises, requiring up to 96 hours for full recovery.
The results show that different modes of the same exercise present unique challenges to each of the muscle groups involved. Prime movers tend to be more similarly affected, whereas secondary muscle groups may vary greatly in the extent they are activated, produce force, and experience muscle soreness.
When planning the training frequency for a given muscle group, take into consideration that the exercises selected may lend themselves to different training frequency. It’s a good idea to alternate between highly taxing exercises like the barbell bench and less taxing exercises like dumbbell benches throughout the week. – FLEX