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Cooperative Grouping: Ideas for Effective Classroom Practice

Author(s): Nancy Moreno, PhD, Barbara Tharp, MS, and Judith Dresden, MS.
Showing Results for: collaboration Return to Presentation

Human Study

This slide presents results obtained from a study published in collaboration with Dr. Per Tesch, Department of Physiology and Pharmacology at the Karolinska Research Institute in Stockholm, Sweden. Subjects were randomly divided into three groups. One group was subjected to the unilateral lower limb suspension (ULLS) model. Recall that this manipulation is designed to unload the leg so that it cannot perform any weight-bearing activity. A second group also was subjected to ULLS, but this group received resistance exercise every three days to provide heavy loading stimuli to the thigh muscles. A third group did not receive the ULLS treatment, but received the same resistance exercise loading treatment as the second group. The findings clearly indicate the following.

  1. ULLS treatment induces muscle atrophy (indicated by the decreased muscle volume) as well as a reduction in strength.
  2. This atrophy response was significantly meliorated by the resistance exercise program.
  3. Resistance exercise induces muscle hypertrophy and increases in strength among individuals undergoing normal weight bearing activity.

This experiment demonstrates that periodic high levels of muscle loading have a profound effect on skeletal muscle, especially in individuals who undergo states of non-weight bearing activity. This suggests that with appropriate training programs, muscle mass and strength can be preserved in astronauts experiencing long term space travel. However, the prescription may need to be altered because some missions will be longer than the five-week duration of the present study.

Do you think exercises, such as walking and jogging, would be successful in preventing muscle atrophy and loss of strength?

Suggested Reading:
Haddad, F., Baldwin, K. M., & Tesch, P. A. (2005). Pretranslational markers of contractile protein expression in human skeletal muscle: effects of limb unloading plus resistance exercise. J. Appl. Physiol. 98: 46-52.

This slide illustrates what happens to the change in muscle size, and the change in muscle strength when individuals undergo an unloading stimulus (unilateral limb suspension model). Note that the muscles indeed get smaller and weaker, as shown by the bar graph going down into the negative range, relative to normal. You can blunt that atrophy response and create a positive effect, in terms of muscle size and strength, by providing brief bouts of resistance exercise to individuals undergoing the limb suspension stimulus. In fact, this approach is almost as effective as if you gave resistance exercise to an individual going through normal weight bearing activity. These outcomes give us hope that we can enable our astronauts to try to keep themselves healthy by these various exercise prescriptions.