Repeated bouts of load carriage alter indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in male soldiers
Abstract Soldiers are often required to carry heavy external loads over multiple days, which may degrade physical performance. We investigated the effects of repeated load carriage bouts on indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in active‐duty...
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| Format: | Article |
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Wiley
2025-08-01
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| Series: | Physiological Reports |
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| Online Access: | https://doi.org/10.14814/phy2.70268 |
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| author | Chad R. Straight Kari L. McKenzie Ava L. Sargent Kenneth Racicot Adrienne Hatch‐McChesney Tshinanne V. Ndou Kevin S. O'Fallon |
| author_facet | Chad R. Straight Kari L. McKenzie Ava L. Sargent Kenneth Racicot Adrienne Hatch‐McChesney Tshinanne V. Ndou Kevin S. O'Fallon |
| author_sort | Chad R. Straight |
| collection | DOAJ |
| description | Abstract Soldiers are often required to carry heavy external loads over multiple days, which may degrade physical performance. We investigated the effects of repeated load carriage bouts on indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in active‐duty infantrymen. Fourteen male soldiers (age = 24.6 ± 1.1 y; BMI = 25.7 ± 0.7 kg/m2) underwent a 5‐day protocol, consisting of baseline/familiarization, 3 load carriage bouts, and a recovery day. There were reductions in maximal voluntary contraction strength (p < 0.05), with the knee flexors and trunk extensors showing the greatest declines. Each load carriage bout produced an inflammatory response, including increases in leukocyte subtypes (neutrophils and monocytes) and monocyte chemoattractant protein‐1 (p < 0.05). At the end of the protocol, serum liver enzymes were elevated, and erythrocytes and hematocrit were lower than baseline (p < 0.05). In addition, greater circulating leukocytes at baseline predicted lower knee and trunk torque during recovery. Repeated bouts of load carriage reduce muscle strength and cause inflammation consistent with exercise‐induced muscle damage, alter liver function tests, and decrease oxygen‐carrying capacity in male soldiers, which could compromise readiness for prolonged and/or intense military operations. |
| format | Article |
| id | doaj-art-9dac3ccc990c4013b24f865b5ff4cab1 |
| institution | DOAJ |
| issn | 2051-817X |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Wiley |
| record_format | Article |
| series | Physiological Reports |
| spelling | doaj-art-9dac3ccc990c4013b24f865b5ff4cab12025-08-20T03:07:32ZengWileyPhysiological Reports2051-817X2025-08-011315n/an/a10.14814/phy2.70268Repeated bouts of load carriage alter indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in male soldiersChad R. Straight0Kari L. McKenzie1Ava L. Sargent2Kenneth Racicot3Adrienne Hatch‐McChesney4Tshinanne V. Ndou5Kevin S. O'Fallon6Combat Capabilities Development Command Soldier Center Natick Massachusetts USACombat Capabilities Development Command Soldier Center Natick Massachusetts USACombat Capabilities Development Command Soldier Center Natick Massachusetts USACombat Capabilities Development Command Soldier Center Natick Massachusetts USAUnited States Army Research Institute of Environmental Medicine Natick Massachusetts USACombat Capabilities Development Command Soldier Center Natick Massachusetts USACombat Capabilities Development Command Soldier Center Natick Massachusetts USAAbstract Soldiers are often required to carry heavy external loads over multiple days, which may degrade physical performance. We investigated the effects of repeated load carriage bouts on indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in active‐duty infantrymen. Fourteen male soldiers (age = 24.6 ± 1.1 y; BMI = 25.7 ± 0.7 kg/m2) underwent a 5‐day protocol, consisting of baseline/familiarization, 3 load carriage bouts, and a recovery day. There were reductions in maximal voluntary contraction strength (p < 0.05), with the knee flexors and trunk extensors showing the greatest declines. Each load carriage bout produced an inflammatory response, including increases in leukocyte subtypes (neutrophils and monocytes) and monocyte chemoattractant protein‐1 (p < 0.05). At the end of the protocol, serum liver enzymes were elevated, and erythrocytes and hematocrit were lower than baseline (p < 0.05). In addition, greater circulating leukocytes at baseline predicted lower knee and trunk torque during recovery. Repeated bouts of load carriage reduce muscle strength and cause inflammation consistent with exercise‐induced muscle damage, alter liver function tests, and decrease oxygen‐carrying capacity in male soldiers, which could compromise readiness for prolonged and/or intense military operations.https://doi.org/10.14814/phy2.70268immune cellsinflammationmilitaryperformanceskeletal muscle |
| spellingShingle | Chad R. Straight Kari L. McKenzie Ava L. Sargent Kenneth Racicot Adrienne Hatch‐McChesney Tshinanne V. Ndou Kevin S. O'Fallon Repeated bouts of load carriage alter indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in male soldiers Physiological Reports immune cells inflammation military performance skeletal muscle |
| title | Repeated bouts of load carriage alter indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in male soldiers |
| title_full | Repeated bouts of load carriage alter indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in male soldiers |
| title_fullStr | Repeated bouts of load carriage alter indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in male soldiers |
| title_full_unstemmed | Repeated bouts of load carriage alter indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in male soldiers |
| title_short | Repeated bouts of load carriage alter indirect markers of exercise‐induced muscle damage, liver enzymes, and oxygen‐carrying capacity in male soldiers |
| title_sort | repeated bouts of load carriage alter indirect markers of exercise induced muscle damage liver enzymes and oxygen carrying capacity in male soldiers |
| topic | immune cells inflammation military performance skeletal muscle |
| url | https://doi.org/10.14814/phy2.70268 |
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