|In view of the fact that there are women in the photos, it should be obvious that these are not the study subjects ;-)|
Well, I have to admit that I was similarly surprised when I read that jumping had a similar beneficial effect on the bones as resistance training in relatively young (25-60 year-old) male subjects in a recent study from the University of Missouri (Horton. 2015).
As a cursory glance at the abstract reveals, the "jumping training" the subjects did 3 times per week consisted of jumps with progressing intensity (e.g. jump off box more “intense” than squat jump) and complexity of the movement (e.g., single-leg jump more intense than double-leg jump).
- Weeks 1–2 were comprised of low-intensity jumps (10 repetitions of squat jump, forward hop, split squat and lateral box push-off jumps);
- Weeks 3–4 also included moderate-intensity jumps (10 repetitions of 6–8 different jumps, which included bounding, lateral bounding, box jump, lateral hurdle, zig-zag jumps, or single-leg lateral hurdle and 2 randomly selected low-intensity jumps);
- Weeks 5-6 also included high-intensity jumps like depth jumps and jumps off a box (10 repetitions of 10–12 different jumps, which included depth jumps and jumps off a box and 8–10 randomly selected low- and moderate-intensity jumps).
- Week 7 was a rest week after wards the cycle was repeated for 8 cycles.
" The RT intervention included exercises that load the hip and spine: squats, bent-over-row, modified dead lift, military press, lunges, and calf raises. To minimize risk of injury and to account for strength adaptations as a result of strength training improvements, the RT intervention also used a progressive intensity design based on a 6-week cycle followed by a rest week; a total of 8 cycles were completed" (Hinton. 2015).As it was the case for the JUMP group, the intensity increased gradually over a 6-week cycle based on new 1-RM tests that were made every 2nd week. In that,...
"[...] weeks 1–2 were light intensity, consisting of one warm-up set of 10 repetitions at 20% 1RM and 3 sets of 10 repetitions at 50% 1RM; weeks 3–4 were moderate intensity with one warm-up set of 10 repetitions at 20% 1RM, two sets of 10 repetitions at 60% 1RM, and one set of 6–8 repetitions at 70–75% 1RM; and weeks 5–6 were high-intensity, starting with one warm-up set of 10 repetitions at 20% 1RM, followed by 2 sets of 10 repetitions at 60% 1RM, and one set of 3–5 repetitions at 80–90% 1RM" (Hinton. 2015)"The participants were instructed to perform the eccentric phase of each lift in 2–3 seconds and to perform the concentric contraction "explosively."
|Figure 1: Despite significantly increased activity levels in almost all subjects, there were no beneficial changes in body composition and accordingly no inter-group differences (Hinton. 2015).|
|Figure 2:1-RM strength from week 0-12; rel. change to baseline in % above the bars (Hinton. 2015).|
The lack of impressive performance gains in the JUMP group does not negate that osteocalcin and OCX, one increases, the other decreases the bone mass improves significantly in subjects in both groups. It does however stand in line with the lack of impressive improvements in bone mass. Improvements that reached statistical significance only in the RT group.
- Bassey, E. J., and S. J. Ramsdale. "Weight-bearing exercise and ground reaction forces: a 12-month randomized controlled trial of effects on bone mineral density in healthy postmenopausal women." Bone 16.4 (1995): 469-476.
- Dalsky, Gail P., et al. "Weight-bearing exercise training and lumbar bone mineral content in postmenopausal women." Annals of internal medicine 108.6 (1988): 824-828.
- Etherington, J., et al. "The effect of weight‐bearing exercise on bone mineral density: a study of female ex‐elite athletes and the general population." Journal of Bone and Mineral Research 11.9 (1996): 1333-1338.
- Hinton, Pamela S., Peggy Nigh, and John Thyfault. "Effectiveness of resistance training or jumping-exercise to increase bone mineral density in men with low bone mass: A 12-month randomized, clinical trial." Bone (2015).