Spot Reduction?

[Greg Everett]

Am J Physiol Endocrinol Metab (September 19, 2006).
doi:10.1152/ajpendo.00215.2006

Are blood flow and lipolysis in subcutaneous adipose tissue influenced by contractions in adjacent muscles in humans?

Bente Stallknecht1, Flemming Dela1, and Jorn Wulff Helge
University of Copenhagen, Copenhagen, Denmark

Aerobic exercise increases whole-body adipose tissue lipolysis, but is
lipolysis higher in subcutaneous adipose tissue (SCAT) adjacent to contracting muscles than in SCAT adjacent to resting muscles? Ten healthy, overnight-fasted males performed one-legged knee extension exercise at 25% of maximal workload (W max) for 30 minutes followed by exercise at 55% Wmax for 120 minutes with the other leg and finally exercised at 85% Wmax for 30 minutes with the first leg.

Subjects rested for 30 minutes between exercise periods. Femoral SCAT blood
flow was estimated from washout of 133Xe and lipolysis was calculated from
femoral SCAT interstitial and arterial glycerol concentrations and blood flow.

In general, blood flow as well as lipolysis was higher in femoral SCAT adjacent to contracting than adjacent to resting muscle (time 15-30 min: blood flow: 25% Wmax: 6.6 ± 1.0 vs. 3.9 ± 0.8 ml 100 g-1 min-1, P < 0.05; 55% Wmax: 7.3 ± 0.6 vs. 5.0 ± 0.6, P < 0.05; 85% Wmax: 6.6 ± 1.3 vs. 5.9 ± 0.7, P > 0.05; lipolysis: 25% Wmax: 102 ± 19 vs. 55 ± 14 nmol 100 g-1 min-1, P = 0.06; 55% Wmax: 86 ± 11 vs. 50 ± 20, P > 0.05; 85% Wmax: 88 ± 31 vs. -9 ± 25, P < 0.05).

In conclusion, blood flow and lipolysis are generally higher in SCAT adjacent to contracting than adjacent to resting muscle irrespective of exercise intensity. Thus, specific exercises can induce "spot lipolysis" in adipose tissue.