(40) BARBELL BACK SQUATS DO NOT ILLICIT CHANGES IN HEPCIDIN, IRON, OR IL-6 IN RESISTANCE-TRAINED WOMEN

Background: Hepcidin is a peptide hormone responsible for the regulation of iron. When hepcidin levels are elevated, iron reabsorption is shunted, thus, decreasing iron concentration. Endurance exercise can increase hepcidin and may lead to exercise-induced iron deficiencies. Further, hepcidin and IL-6 concentrations are positively correlated. The impact of resistance exercise on hepcidin concentration is unclear.

Purpose: To evaluate the acute effect of resistance exercise on circulating hepcidin, iron, and IL-6 concentrations in resistance trained women.

Methods: 12 resistance trained women (age:23.7±4.1 years; training age: 5.0±2.2 years; height: 160±6.0 cm; body mass 64.1±10.8 kg; body fat percentage 24.3±4.8%; fat free mass: 49.0±6.6 kg) participated in this repeated measures, counterbalanced study. Participants completed 3 sessions: familiarization (1), traditional sets (2 or 3), and rest redistribution (RR) sets (2 or 3). In session 1, body composition was measured via air displacement plethysmography and barbell back squat strength via 1-repetition maximum (1RM). In the 2^nd and 3^rd sessions, either traditional (TR) sets or RR sets of barbell back squat exercise were completed following a standard warm-up. TR and RR included 40 repetitions at 70% of 1RM. For TR, 4 sets of 10 repetitions were performed with 120 seconds inter-set rest. For RR, 4 sets of 10 repetitions were performed with 30 seconds of intra-set rest after 5 repetitions and 90 seconds inter-set rest. Blood samples were collected at baseline, 5, 15, 30, and 60 minutes, 24 hours, and 48 hours post-exercise. Hepcidin and IL-6 were assessed through ELISA, and iron was assessed through colorimetric assay in an auto analyzer. Condition by time repeated measures analysis of variance (RMANOVA) was used for analysis. Pearson correlations between hepcidin, iron, and IL-6 were evaluated. Alpha level was set at p< 0.05.

Results: No differences were observed for condition (iron: p=0.897; hepcidin: p=0.401; IL-6: p=0.933), time (iron: p=0.601; hepcidin: p=0.084; IL-6: p=0.360), and condition x time interaction (iron: p=0.329; hepcidin: p=0.490; IL-6: p=0.328) in variables tested. Further, no meaningful correlations between variables were identified.

Conclusion: Based upon the current results, TR and RR do not elicit acute changes in circulating hepcidin, iron, or IL-6 in resistance trained women. Relationships between hepcidin, iron, and IL-6 do not appear to exist following resistance training activity. Previous literature has shown IL-6 increases as a result of the number of repetitions performed, not the intensity of the repetitions; therefore, 40 repetitions may be an insufficient volume to elicit changes in IL-6 in this population. Further, the way in which rest is distributed throughout the repetitions does not appear to impact hepcidin, iron, and IL-6 responses with the current volume. Practical applications: When working with resistance trained women, who may be at risk for an iron deficiency, it does not appear that resistance exercise will increase hepcidin levels sufficiently to result in an exercise-related induced iron deficiency. It is recommended practitioners note the volume selected in a resistance training session, as a greater number than the present study may elicit changes in the variables measured.

Acknowledgements: None