Effects and reproducibility of aerobic and resistance exercise on appetite and energy intake in young, physically active adults
 
 
Journal Title (Medline/Pubmed accepted abbreviation):  Appl. Physiol. Nutr. Metab.
Year: 2010
Volume: 35
Page numbers: 842-847
doi (if applicable):  10.1139/H10-072

Summary of Background and Research Design

Background: “Anorexia of exercise” describes the phenomenon that hunger may decrease after exercise for up to 60 min. There is some evidence supporting that resistance exercise (REx) reduces appetite and that aerobic exercise (AEx) has an even greater effect, but these observations have not been consistent.

Hypothesis: “Anorexia of exercise” describes the phenomenon that hunger may decrease after exercise for up to 60 min. There is some evidence supporting that resistance exercise (REx) reduces appetite and that aerobic exercise (AEx) has an even greater effect, but these observations have not been consistent.

Secondary research goal:To assess the reproducibility of an ad libitum meal energy intake protocol.
 
Subjects:Physically active males (n=9) and females (n=10), age 22.3 ± 2.5

Experimental design: randomized cross-over design for three session types: REx, AEx, and control

Treatments and protocol:Subjects were asked to consume a meal of their choice 3 hrs before arriving at the laboratory. For the AEx session, subjects completed 35 min of cycling on an ergometer at 70% of their heart rate reserve (which equals about 80% VO2max) with a 5 min warm up and cool down. For the REx session, they performed 2 sets of 10 repetitions and a third set to voluntary fatigue (or 12 reps) at 70% of their 1RM for chest press, double leg press, seated leg extension, seated leg curl, and seated row (as determined previously). There was 1 min rest in between sets. During the control session, subjects sat in the exercise room for the same duration.Subjects were asked to consume a meal of their choice 3 hrs before arriving at the laboratory. For the AEx session, subjects completed 35 min of cycling on an ergometer at 70% of their heart rate reserve (which equals about 80% VO2max) with a 5 min warm up and cool down. For the REx session, they performed 2 sets of 10 repetitions and a third set to voluntary fatigue (or 12 reps) at 70% of their 1RM for chest press, double leg press, seated leg extension, seated leg curl, and seated row (as determined previously). There was 1 min rest in between sets. During the control session, subjects sat in the exercise room for the same duration.
                Thirty min after the exercise session subjects consumed ad libitum cold pasta salad for 30 min with 237 mL water. During this time, subjects were silent, supervised, and partitioned from others while eating.   The subjects were aware that their portion sizes were being monitored. However, it was not stated in the article how much knowledge the subjects might have had regarding the research hypothesis.
                Hunger was assessed 60 min pre-testing (-60 min), immediately after exercising (+45 min), before they began the meal (+75 min), and 30 min after the first bite (+105 min).

Summary of research findings:
  • Mean energy intake- AEx: 897 ± 96 kcal; REx: 924 ± 95 kcal; CON 784 ± 89 kcal. When adjusted for energy expenditure (relative energy intake, REI), the trends were similar but AEx led to a significantly lower REI than REx and the control (p<0.0001).
  • Perceived hunger was reduced immediately following AEx but not REx compared to the control. Both exercise bouts caused a significant increase in hunger between the +45 and +75 time points, however.
  • The reproducibility of this protocol is good, with an intra-class correlation (ICC) = 0.869 for control, 0.899 for AEx, and 0.894 for REx.

Interpretation of findings/Key practice applications:

 The “anorexia of exercise” phenomenon was noted after AEx and not REx, though the feeling was transient. This study therefore provides additional evidence that “anorexia of exercise” does not apply to resistance training. Further, the study demonstrates that, despite transient decreases in perceived hunger immediately following exercise, the exercise contributed to increased, rather than decrease energy intake.

Limitations:

The duration of the exercise was the same for the REx and the AEx sessions, but not the energy expended at each session. A study that explores “anorexia of exercise” between these two types of exercise during which the same number of calories is burned is needed.
Google Tracking Google Plus Tracking Twitter Tracking