For the December 2015 volume of MSSE, I am highlighting three articles that deal with very different topics of unique interest.
First, using data from an ongoing prospective observational study, Drenowatz et al. found that the effects of exercise on body composition differ by weight category and exercise type. Normal weight participants experienced an increase in lean mass with higher exercise volume, whereas overweight/obese participants experienced a reduction in fat mass, regardless of what type of exercise training (i.e., aerobic or resistance) was performed. The key finding of the study, however, was that resistance exercise had a greater effect to reduce fat mass in overweight/obese participants than did aerobic exercise. These results suggest that even though aerobic exercise has been the dominant choice in exercise interventions, resistance exercise is an attractive option for overweight/obese participants to improve their body composition and increase quality of life.
There has been a recent global explosion of nonceliac athletes adopting a gluten-free diet (GFD), even in the absence of clinical assessment and/or indications. Over 40% of nonceliac athletes report adhering to this diet at least half of the time, with the belief that gluten causes symptoms representative of ill health, gastrointestinal distress, and that its avoidance improves athletic performance. In this issue, Lis et al. report the first placebo-controlled double-blind cross-over intervention to determine the effects of a GFD in nonceliac athletes. Their short-term (7-days) GFD had no effect on markers of inflammation (IL-1β, IL-6, IL-8, IL-10, IL-15 and TNF-α), acute intestinal injury (intestinal fatty acid binding protein), gastrointestinal symptoms, perceptual wellbeing or exercise (cycling) performance. These findings reveal no evidence that athletes without clinical diagnosis of celiac disease or gluten intolerance will incur any health or performance benefit by adopting a GFD.
In a biomechanics study, Danielsen et al. analyzed the mechanical energy fluctuations of the body in relationship to work during cross-country skiing with the double-poling technique. They found that the work performed by the muscles and tendons of the whole body during a poling cycle was divided approximately equally between two phases, propulsion and recovery. During recovery, the lower extremities performed internal work that enhanced the mechanical energy of the body, and, this mechanical energy was transformed directly into external work (“falling on the poles”), which was added to the external work contributed by the upper extremities during the propulsion phase of the subsequent poling cycle. This unique movement pattern differs in an essential manner from classic forms of locomotion such as walking and running which are characterized by inverted pendulum or spring–mass types of movement. It appears likely that appropriate timing and coordination are of utmost importance for an optimal utilization of mechanical energy for propulsion (external work).
L. Bruce Gladden