Anthropometric changes in adolescents with anorexia nervosa in response to resistance training

The follow-up of anthropometric percentiles such as triceps and mid-thigh skinfold thickness (TSF, MTSF), mid-upper arm and mid-thigh circumferences (MUAC, MTC), and arm and mid-thigh muscle areas (AMA, MTMA) after a resistance training might allow for detecting nutritional progress of fat and muscular tissue during the treatment of anorexia nervosa restricting (AN-R) type patients.

A total of 44 AN-R patients were randomized for control (CG 13.0 ± 0.6 years) and intervention (IG 12.7 ± 0.7 years) groups after hospitalization. The intervention group underwent a resistance training program of 8 weeks following the guidelines for healthy adolescents (3 days/week; 70 % of 6 RM). All measurements were obtained prior to starting the program (PRE) and after 8 weeks of training (POST) in both groups. TSF, MTSF, MUAC, and MTC were measured, and AMA and MTMA were calculated. Data were matched with percentile tables for general population. Changes were assessed using statistical tests for categorical data.

The distribution of percentile categories within the groups did not differ statistically after 8 weeks (p > 0.05). After training, 73 % of the patients were at the same percentile interval of MUAC, 18 % higher and 9 % lower, while 30 % of CG was at lower percentile categories. Further, 54 % of the IG patients remained at the same percentile interval of MTC after training, and 36 % higher, while 20 % were at lower categories in the CG. The AMA increased (32 %) after training or remained at the same interval (59 %) in the IG, while the IG showed greater frequency of percentile decreases (45 %).

Anthropometric measurements could be useful for assessing muscle status in AN-R patients during the treatment process. However, exact standard deviation scores should be used instead of percentile categories to increase the sensitivity to changes in TSF, MTSF, MUAC, MTC or AMA.