Iron plays an important role in thyroid hormone metabolism; thus, iron deficiency anemia may lead to alterations in resting metabolic rate (RMR). Based on this premise, two iron-deficient-anemic female athletes, 18 (A 1) and 21 (A2) years of age, were supplemented with 23 mg/day of elemental iron to assess its effects on iron and thyroid hormone status and RMR at 0, 8, and 16 weeks. Anemia was clinically corrected in both subjects (hemoglobin: Al = 11.0 to 13.0 to 12.6 g/dL and A2 = 11.5 to 13.9 to 12.6 g/dL, 0 to 8 to 16 weeks, respectively). Serum ferritin (SF) concentration also improved in both subjects (Al: 5.0 to 11.0 to 15.0 ng/dL and A2: 5.0 to 16.0 to 20.0 ng/dL; 0 to 8 to 16 weeks, respectively); however, 16 weeks of iron supplementation did not fully replete iron stores. A2 increased dietary iron and ascorbic acid intakes from 8 to 16 weeks, possibly accounting for her higher SF concentrations. RMR and total thyroxine changed over time: Al increased while A2 decreased in these variables. Although clinical correction of iron deficiency anemia occurred after 16 weeks of low-level iron supplementation, RMR and thyroid hormone metabolism were oppositely affected in the two subjects.
Penny Harris Rosenzweig and Stella L. Volpe
Mary P. Miles, Sherri D. Pearson, Jan M. Andring, Jessy R. Kidd and Stella L. Volpe
The purpose of this investigation was to determine whether carbohydrate supplementation during the frst 2 d post exercise recovery influenced the inflammation (IL-6, C-reactive protein [CRP], and cortisol) and muscle-damage responses. Eight participants performed a high-force eccentric elbow-fexion exercise to induce muscle soreness and inflammation and then consumed carbohydrate (0.25 g·kg−1·h−1) or an equal volume of placebo during hours 0–12 and 24–36 post exercise in a double-blind, crossover protocol. Muscle soreness; mid brachial arm circumference; blood glucose, IL-6, CRP, cortisol, and creatine-kinase (CK) activity; and maximal force production were measured pre exercise and 4, 8, 12, 24, 48, and 120 h post exercise. Plasma IL-6 increased, F(5) = 5.27, P < 0.05, 8 h post exercise, with no difference between carbohydrate and placebo conditions. Changes in muscle soreness, arm circumference, strength, and serum CK activity were consistent with small amounts of muscle damage and did not differ between conditions. The authors conclude that carbohydrate supplementation during recovery from soreness-inducing exercise does not influence the delayed IL-6 response temporally linked to inflammation or indications of muscle damage. Thus, increased carbohydrate consumption at levels consistent with recommendations for replenishing glycogen stores does not impair or promote the immune and muscle responses.
Russell Jago, Robert G. McMurray, Stanley Bassin, Laura Pyle, Steve Bruecker, John M. Jakicic, Esther Moe, Tinker Murray and Stella L. Volpe
Two pilot studies were conducted to examine whether 6th grade students can achieve moderate to vigorous physical activity (MVPA) from 1) activity-based physical education (AB-PE) with 585 participants and 2) a curricular-based (CB-PE) program with 1,544 participants and randomly sampled heart rates during lessons. AB-PE participants spent between 54–66% with a heart rate >140 bpm. CB-PE participants spent between 49–58% with a heart rate >140 bpm. Girls’ mean heart rate was 3.7 bpm lower than the boys. PE can be readily modified so that students spend more than 50% of time in MVPA.