Physical performance responses during 72 h of military operational stress

Nindl, Bradley C.; Leone, Cara D.; Tharion, William J.; Johnson, Richard F.; Castellani, John W.; Patton, John F.; Montain, Scott J.

doi:10.1097/00005768-200211000-00019

Cited by 129 publications

(149 citation statements)

References 26 publications

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“…The major contributor to energy expenditure was sustained aerobic exercise associated with nightly road marches, land navigation, and patrolling activities (estimated exercise intensity of 30-40% maximal oxygen consumption). Other results from this research study have been published elsewhere (7,30).…”

Section: Subjectsmentioning

confidence: 79%

Differential responses of IGF-I molecular complexes to military operational field training

Nindl¹,

Castellani²,

Young³

et al. 2003

Journal of Applied Physiology

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. Differential responses of IGF-I molecular complexes to military operational field training. J Appl Physiol 95: 1083-1089, 2003; 10.1152/japplphysiol. 01148.2002.-Insulin-like growth factor (IGF) I and IGF binding proteins (IGFBPs) modulate metabolic activity and tissue repair and are influenced by nutritional status. IGF-I circulates in free, ternary [IGF-I ϩ IGFBP-3 ϩ acid labile subunit (ALS)], and binary (IGF-I ϩ IGFBP) molecular complexes, and the relative proportions regulate IGF-I extravascular shifting and bioavailability. This study examined the hypothesis that sustained physical activity and sleep deprivation superimposed on a short-term energy deficit would alter the IGFBP concentrations and alter the proportions of IGF-I circulating in ternary vs. binary molecular complexes. Components of the IGF-I system (total and free IGF-I; IGFBP-1, -3, and ALS; nonternary IGF-I and IGFBP-3), biomarkers of metabolic and nutritional status (transferrin, ferritin, prealbumin, glucose, free fatty acids, glycerol, ␤-hydroxybutyrate), and body composition were measured in 12 men (22 Ϯ 3 yr, 87 Ϯ 8 kg, 183 Ϯ 7 cm, 20 Ϯ 5% body fat) on days 1, 3, and 4 during a control and experimental (Exp) period. During Exp, subjects performed prolonged work (energy expenditure of ϳ4,500 kcal/day) with caloric (1,600 kcal/day) and sleep (6.2 h total) restriction. IGF-I and IGFBP-3 were measured by immunoassay before and after immunoaffinity depletion of ALS-based complexes (i.e., ternary complex removal). Exp produced losses in body mass (Ϫ3.0%), lowered total IGF-I (Ϫ24%), free IGF-I (Ϫ42%), IGFBP-3 (Ϫ6%), nonternary IGF-I (Ϫ27%), and IGFBP-3 (Ϫ16%), and increased IGFBP-1 (256%). No Exp effects were observed for ALS. No changes were observed in the proportion of IGF-I circulating in free (ϳ1.2%), ternary (ϳ87.4%), or nonternary (ϳ11.4%) molecular complexes. During Exp, glucose concentrations were lower on day 3, but days 1 and 4 were statistically similar. In conclusion, during a short-term energy deficit in young, healthy men, 1) IGF-I system components differentially respond (both in direction and magnitude) to a given metabolic perturbation and 2) the relative proportion of IGF-I sequestered in ternary vs. nonternary molecular complexes appears to be well maintained.

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Section: Subjectsmentioning

confidence: 79%

Differential responses of IGF-I molecular complexes to military operational field training

Nindl¹,

Castellani²,

Young³

et al. 2003

Journal of Applied Physiology

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“…This type of dietary practice has been shown to impair performance in a number of military relevant tasks (Nindl et al 2002;Montain and Young 2003). Additionally, athletes and dieters might voluntarily restrict their energy intake to induce a reduction in body mass and/ or body fat.…”

Section: Introductionmentioning

confidence: 99%

Electrolyte supplementation during severe energy restriction increases exercise capacity in the heat

2015

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PURPOSE:This study examined the effects of sodium chloride and potassium chloride supplementation during 48 h severe energy restriction on exercise capacity in the heat. METHODS:Nine males completed three 48 h trials: adequate energy intake (100% requirement), adequate electrolyte intake (CON); restricted energy intake (33% requirement), adequate electrolyte intake (ER-E); and restricted energy intake (33% requirement), restricted electrolyte intake (ER-P). At 48 h, cycling exercise capacity at 60% V  O 2 peak was determined in the heat (35.2°C; 61.5% relative humidity). RESULTS:Body mass loss during the 48 h was greater during ER-P (2.16 (0.36) kg) than ER-E (1.43 (0.47) kg; P<0.01) and CON (0.39 (0.68) kg; P<0.001), as well as greater during ER-E than CON (P<0.01). Plasma volume decreased during ER-P (P<0.001), but not ER-E or CON. Exercise capacity was greater during CON (73.6 (13.5) min) and ER-E (67.0 (17.2) min) than ER-P (56.5 (13.1) min; P<0.01), but was not different between CON and ER-E (P=0.237). Heart rate during exercise, was lower during CON and ER-E than ER-P (P<0.05). CONCLUSIONS:These results demonstrate that supplementation of sodium chloride and potassium chloride during energy restriction attenuated the reduction in exercise capacity that occurred with energy restriction alone. Supplementation maintained plasma volume at pre-trial levels and consequently prevented the increased heart rate observed with energy restriction alone. These results suggest that water and electrolyte imbalances associated with dietary energy and electrolyte restriction might contribute to reduced exercise capacity in the heat.

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“…In military operations soldiers are often exposed to various stressors, such as prolonged and strenuous physical exercise, energy and Xuid deWciency, extreme ambient temperature, and sleep deprivation (Nindl et al 2002;Opstad 1995). Heavy military Weld exercises lasting less than 1 week have been shown to induce increases in basal concentrations of circulating cortisol (COR) (Opstad 1991(Opstad , 1992(Opstad , 1994 and GH (Opstad 1994), and decreases in serum insulin (INS) (Opstad 1991), testosterone (TES) (GomesMerino et al 2003;Opstad 1992Opstad , 1994, thyroid hormone levels (Opstad 1992(Opstad , 1994 and insulin-like growth factor (Nindl et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Hormonal responses during a prolonged military field exercise with variable exercise intensity

et al. 2007

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The purpose of the present study was to test the hypothesis that the magnitude of hormonal concentration alterations during a prolonged military field exercise with constant energy intake (EI) is influenced by changes in energy deficit (ED) induced by varying the exercise intensity. Basal serum hormone concentrations were measured in a group of healthy young male volunteers (n = 7) during a 20-day field exercise. During the first week of the exercise, the average ED was 4,000 kcal/day (P-I), in the second week only 450 kcal/day (P-II), and in the last week 1,000 kcal/day (P-III). During the first 5 days of the field exercise, significant increases in cortisol (COR, +32%) and growth hormone (GH, +616%) concentrations were observed, while insulin (INS, -70%), total testosterone (TES, -27%), free testosterone (TES(free), -26%) decreased. However, after these initial responses, COR and GH returned to the pre-exercise level by the beginning of P-II. Also TES and TES(free) recovered to the pre-exercise level by the beginning of P-III, and INS by the end of P-III. The concentration of TES (+29%) increased above the pre-exercise level by the beginning of P-III. Serum thyroxin (T(4)) concentration was significantly lesser (-12%) and urine urea concentration significantly higher (+78%) after the field exercise than before it. Therefore, it can be concluded that the lower levels of ED in the second and third phase (ED <1,000 kcal/day) allowed recovery of hormonal changes observed in the first phase with ED much greater than 1,000 kcal/day.

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Physical performance responses during 72 h of military operational stress

Abstract: Decrements in performance during SUSOPS are primarily restricted to tasks that recruit muscles that are over-utilized without adequate recovery. General military skill tasks and occupational physical performance tasks are fairly well maintained.

Cited by 129 publications

References 26 publications

Differential responses of IGF-I molecular complexes to military operational field training

Differential responses of IGF-I molecular complexes to military operational field training

Electrolyte supplementation during severe energy restriction increases exercise capacity in the heat

Hormonal responses during a prolonged military field exercise with variable exercise intensity

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