Skeletal responses to an all-female unassisted Antarctic traverse

O’Leary, Thomas J.; Gifford, Robert M.; Double, Rebecca L.; Reynolds, Rebecca M.; Woods, David R.; Wardle, Sophie L.; Greeves, Julie P.

doi:10.1016/j.bone.2019.02.002

Cited by 16 publications

(18 citation statements)

References 43 publications

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“…Laboratory studies show that short-term (5 days) low energy availability had no effect on βCTX in men (30). Military studies demonstrate no effect of energy deficit on the βCTX response to 8 weeks US Army Ranger training in men (20), or a 61 day Antarctic traverse in women (21). Similar to our study, reduced βCTX has been reported in response to 13 weeks of infantry basic military training in men and women (22).…”

Section: Markers Of Bone Formation and Resorptionsupporting

confidence: 85%

“…Procollagen type 1 Nterminal propeptide  a measure of type I collagen synthesis by the osteoblast ( 29 low energy availability has no effect on P1NP production in men (30). We recently observed no change in P1NP in women following a 61 day Antarctic traverse, although the follow-up measurement was made 4 days after the expedition (21). Similar to this study, P1NP was unchanged (22,23) or increased (25) (23,25).…”

Section: Markers Of Bone Formation and Resorptionsupporting

confidence: 73%

“…Markers of bone formation and whole body mineral content (BMC) decreased in men with energy deficits of ~4.2 MJ•d -1 during 8 weeks of US Army Ranger training (12,20). Furthermore, 61 days of energy deficit (13% body mass loss) during an Antarctic crossing decreased bone formation and reduced areal bone mineral density at the axial skeleton of female British soldiers (21). Conversely, basic military training, which elicits only mild energy deficiencies, improved tibial bone density, bone macro-and microstructure, and estimated bone strength after 8 to 13 weeks (22)(23)(24).…”

Section: Introductionmentioning

confidence: 99%

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Supplementary Energy Increases Bone Formation during Arduous Military Training

O’Leary¹,

Walsh²,

Casey³

et al. 2020

Medicine &Amp; Science in Sports &Amp; Exercise

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To investigate the effect of supplementary energy on bone formation and resorption during arduous military training in energy deficit. Methods: Thirty male soldiers completed an 8-week military combat course (mean ± SD, age 25 ± 3 years, height 1.78 ± 0.05 m, body mass 80.9 ± 7.7 kg). Participants received either the habitual diet (control group, n = 15) or an additional 5.1 MJ•d -1 to eliminate the energy deficit (supplemented group, n = 15). Circulating markers of bone formation and resorption, and reproductive, thyroid, and metabolic status, were measured at baseline, and week 6 and 8 of training. Results: Bone ALP decreased in controls (−4.4 ± 1.9 μg•L -1 ) and increased in the supplemented group (16.0 ± 6.6 μg•L -1 ), between baseline and week 8 (P < 0.001). P1NP increased between baseline and week 6 for both groups (5.6 ± 8.1 μg•L -1 , P = 0.005). βCTX decreased between baseline and week 8 for both groups (−0.16 ± 0.20 μg•L -1 , P < 0.001). Prolactin increased from baseline to week 8 for the supplemented group (148 ± 151 IU•L -1 , P = 0.041). The increase in adiponectin from baseline to week 8 was higher in controls (4.3 ± 1.8 mg•L -1 , P < 0.001) than the supplemented group (1.4 ± 1.0 mg•L -1 , P < 0.001). IGF binding protein-3 was lower at week 8 than baseline for controls (−461 ± 395 ng•mL -1 , P < 0.001). Conclusion: The increase in bone ALP, a marker of bone formation, with supplementation supports a role of energy in osteoblastic activity; the implications for skeletal adaptation and stress fracture risk is unclear. The mechanism is likely through protecting markers of metabolic, but not reproductive or thyroid, function.

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Section: Markers Of Bone Formation and Resorptionsupporting

confidence: 85%

Section: Markers Of Bone Formation and Resorptionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Supplementary Energy Increases Bone Formation during Arduous Military Training

O’Leary¹,

Walsh²,

Casey³

et al. 2020

Medicine &Amp; Science in Sports &Amp; Exercise

Self Cite

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“…Whole-body bone mineral content and areal BMD losses were also evident after 7-10 months of operational deployment, during which time a 1.9% loss in body mass was observed (116). Six female soldiers who lost 13% body mass over a 61 day crossing of the Antarctic had decreased bone formation and areal BMD at the axial skeleton (117). Tibial macro and microstructure were unchanged suggesting mechanical loading was protective during energy deficiency.…”

Section: Bonementioning

confidence: 95%

Energy Deficiency in Soldiers: The Risk of the Athlete Triad and Relative Energy Deficiency in Sport Syndromes in the Military

2020

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Military personnel experience energy deficit (total energy expenditure higher than energy intake), particularly during combat training and field exercises where exercising energy expenditures are high and energy intake is reduced. Low energy availability (energy intake minus exercising energy expenditure expressed relative to fat free mass) impairs endocrine function and bone health, as recognized in female athletes as the Female Athlete Triad syndrome. More recently, the Relative Energy Deficiency in Sport (RED-S) syndrome encompasses broader health outcomes, physical and cognitive performance, non-athletes, and men. This review summarizes the evidence for the effect of low energy availability and energy deficiency in military training and operations on health and performance outcomes. Energy availability is difficult to measure in free-living individuals but doubly labeled water studies demonstrate high total energy expenditures during military training; studies that have concurrently measured energy intake, or measured body composition changes with DXA, suggest severe and/or prolonged energy deficits. Military training in energy deficit disturbs endocrine and metabolic function, menstrual function, bone health, immune function, gastrointestinal health, iron status, mood, and physical and cognitive performance. There are more data for men than women, and little evidence on the chronic effects of repeated exposures to energy deficit. Military training impairs indices of health and performance, indicative of the Triad and REDS , but the multi-stressor environment makes it difficult to isolate the independent effects of energy deficiency. Studies supplementing with energy to attenuate the energy deficit suggest an independent effect of energy deficiency in the disturbances to metabolic, endocrine and immune function, and physical performance, but randomized controlled trials are lacking.

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“…It has been shown that an energy deficit of this magnitude suppresses the hormone milieu, reduces thyroid function and reduces exercise performance by 9.8% [19]. Reduced thyroid function is of particular concern in military populations due to the suppression on bone formation markers and subsequent risk of a stress fracture [20]. In a crossover study, endurance trained runners undergoing an intense 11-day training programme whilst habitually consuming a diet lower in CHO (5.4 g·kg − 1 ·d − 1 ) experienced a greater deterioration in global mood scores, than when consuming a diet with a higher CHO content (8.5 g·kg − 1 ·d − 1 ) [4].…”

Section: Introductionmentioning

confidence: 99%

Sex differences in dietary intake in British Army recruits undergoing phase one training

Chapman

Roberts

Smith

et al. 2019

Journal of the International Society of Sports Nutrition

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BackgroundBritish Army Phase One training exposes men and women to challenging distances of 13.5 km·d− 1 vs. 11.8 km·d− 1 and energy expenditures of ~ 4000 kcal·d− 1 and ~ 3000 kcal·d− 1, respectively. As such, it is essential that adequate nutrition is provided to support training demands. However, to date, there is a paucity of data on habitual dietary intake of British Army recruits. The aims of this study were to: (i) compare habitual dietary intake in British Army recruits undergoing Phase One training to Military Dietary Reference Values (MDRVs), and (ii) establish if there was a relative sex difference in dietary intake between men and women.MethodResearcher led weighed food records and food diaries were used to assess dietary intake in twenty-eight women (age 21.4 ± 3.0 yrs., height: 163.7 ± 5.0 cm, body mass 65.0 ± 6.7 kg), and seventeen men (age 20.4 ± 2.3 yrs., height: 178.0 ± 7.9 cm, body mass 74.6 ± 8.1 kg) at the Army Training Centre, Pirbright for 8-days in week ten of training. Macro and micronutrient content were estimated using dietary analysis software (Nutritics, Dublin) and assessed via an independent sample t-test to establish if there was a sex difference in daily energy, macro or micronutrient intakes.ResultsEstimated daily energy intake was less than the MDRV for both men and women, with men consuming a greater amount of energy compared with women (2846 ± 573 vs. 2207 ± 585 kcal·day− 1, p < 0.001). Both sexes under consumed carbohydrate (CHO) when data was expressed relative to body mass with men consuming a greater amount than women (4.8 ± 1.3 vs. 3.8 ± 1.4 g·kg− 1·day− 1, p = 0.025, ES = 0.74). Both sexes also failed to meet MDRVs for protein intake with men consuming more than women (1.5 ± 0.3 vs. 1.3 ± 0.3 g·kg− 1·day− 1, p > 0.030, ES = 0.67). There were no differences in dietary fat intake between men and women (1.5 ± 0.2 vs. 1.5 ± 0.5 g·kg− 1·day− 1, p = 0.483, ES = 0.00).ConclusionsDaily EI in men and women in Phase One training does not meet MDRVs. Interventions to increase macronutrient intakes should be considered along with research investigating the potential benefits for increasing different macronutrient intakes on training adaptations.

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Skeletal responses to an all-female unassisted Antarctic traverse

Cited by 16 publications

References 43 publications

Supplementary Energy Increases Bone Formation during Arduous Military Training

Supplementary Energy Increases Bone Formation during Arduous Military Training

Energy Deficiency in Soldiers: The Risk of the Athlete Triad and Relative Energy Deficiency in Sport Syndromes in the Military

Sex differences in dietary intake in British Army recruits undergoing phase one training

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