Bioenergetic Analysis and Fatigue Assessment During the Fran Workout in Experienced Crossfitters.

AIM: To quantify the physiological demands and impact of muscle function t of the Fran workout, one of the most popular CrossFit benchmarks. METHODS: Twenty experienced CrossFitters-16 male: 29 (6) years old and 4 female: 26 (5) years old- performed 3 rounds (with 30-s rests in between) of 21-21, 15-15, and 9-9 front squats to overhead press plus pull-up repetitions. Oxygen uptake and heart rate were measured at baseline, during the workout, and in the recovery period. Rating of perceived exertion, blood lactate, and glucose concentrations were assessed at rest, during the intervals, and in the recovery period. Muscular fatigue was also monitored at rest and at 5 minutes, 30 minutes, and 24 hours postexercise. Repeated-measures analysis of variance was performed to compare time points. RESULTS: Aerobic (52%-29%) and anaerobic alactic (30%-23%) energy contributions decreased and the anaerobic lactic contribution increased (18%-48%) across the 3 rounds of the Fran workout. Countermovement jump height decreased by 8% (-12 to -3) mean change (95% CI), flight duration by 14% (-19 to -7), maximum velocity by 3% (-5 to -0.1), peak force 4% (-7 to -0.1), and physical performance (plank prone 47% [-54 to -38]) were observed. CONCLUSIONS: It appears that the Fran workout is a physically demanding activity that recruits energy from both aerobic and anaerobic systems. This severe-intensity workout evokes substantial postexercise fatigue and corresponding reduction in muscle function.

Supply of Antioxidants vs. Recruit Firefighters' Cellular Immune Status: A Randomized Double-Blinded Placebo-Controlled Parallel-Group Trial.

Background: Physical exercise can affect the immune system. We studied the effect of antioxidants on hematological and immune biomarkers after heavy training. Methods: 24 well-trained and well-fed male firefighters were randomly divided into supplemented and placebo groups, and tested for immunology-related variables using venous blood samples in the fasting state, pre- (M1) and post- (M2) five weeks of daily micronutrient supplementation (15 mg of beta-carotene, 200 mg of vitamin C, 136 mg of vitamin E, 200 µg of selenium, 15 mg of zinc, 100 mg of magnesium). Total leukocytes and a differential count for five populations were determined using standard procedures (MAXM­Beckman Coulter Diagnostics; Brea, CA, USA). Lymphocyte subsets were determined through immunophenotyping. Results: Although all values were within the normal range for healthy adults and athletes in the supplemented group (SG), mean CD3+CD8+, CD8+ and CD16+CD56+ decreased (p < 0.05; small to moderate effects), while mean CD4+, CD19+ and CD4+/CD8+ increased (p < 0.05; small effects) after five-weeks. Regarding the placebo group (PG), higher total leukocyte count (p < 0.05; trivial effect) and natural killer cells percentage (CD16+CD56+; p < 0.05; moderate effect) were observed when comparing M1 and M2. Conclusions: Antioxidants supplementation did not alter well-fed male firefighters recruit firefighters' immune cell response during the five-week physical training program.

Multi-Micronutrient Supplementation and Immunoglobulin Response in Well-Fed Firefighters.

Intensive physical training programs can affect the immune system. This study aims to verify the multi-micronutrient supplementation effects on serum immunoglobulins levels prior to and after a five-week physical training program. Twenty-four male recruit firefighters were randomly allocated into supplemented (with Prisfar Ever-Fit Plus over 35 consecutive days) and placebo groups (n=12 each). Serum immunoglobulins G, A, and M were assessed. Supplementation effect was detected for immunoglobulin G (eta-squared, η 2 : 0.09; p =0.035; power: 0.56), A (η 2 : 0.24; p =0.001; power: 0.95), and M (η 2 : 0.09; p =0.036; power: 0.56). Although immunoglobulin A was different between groups at baseline (mean difference: 42.58; 95%CI: 7.00 to 78.16 mg/dL; p =0.021; d =2.48), within-group (before vs . after five weeks) showed no differences for both supplemented and control groups. In addition, even if immunoglobulin G and M were similar at baseline, immunoglobulin G decreased (mean diff.: 46.4; 95%CI: 6.7 to 86.1 mg/dL; p =0.03; d =0.74) and immunoglobulin M increased (mean diff.: -10.7; 95%CI: -15.8 to -5.5 mg/dL; p =0.001; d =-1.33) in the control group. Although mean values remained within the reference values, changes observed for immunoglobulin G and M may reflect some immune protection for firefighters engaged in recruit training.