Wearing body armour and backpack loads increase the likelihood of expiratory flow limitation and respiratory muscle fatigue during marching

Abstract

The effect of load carriage on pulmonary function was investigated during a treadmill march of increasing intensity. 24 male infantry soldiers marched on six occasions wearing either: no load, 15 kg, 30 kg, 40 kg or 50 kg. Each loaded configuration included body armour which was worn as battle-fit or loose-fit (40 kg only). FVC and FEV 1 were reduced by 6 to 15% with load. Maximal mouth pressures were reduced post load carriage by up to 11% (inspiratory) and 17% (expiratory). Increased ventilatory demands associated with carrying increased mass were met by increases in breathing frequency (from 3 to 26 breathsÁmin À1 ) with minimal changes to tidal volume. 72% of participants experienced expiratory flow limitation whilst wearing the heaviest load. Loosening the armour had minimal effects on pulmonary function. It was concluded that as mass and exercise intensity are increased, the degree of expiratory flow limitation also increases.Practitioner Summary: This study investigated the effect of soldier load carriage on pulmonary function, to inform the trade-off between protection and burden. Load carriage caused an inefficient breathing pattern, respiratory muscle fatigue and expiratory flow limitation during marching. These effects were exacerbated by increases in mass carried and march intensity.

Inspiratory muscle training at sea level improves the strength of inspiratory muscles during load carriage in cold-hypoxia

“…The finding of no change in ΔP imax is in agreement with existing studies (Griffiths and McConnell, 2007;Faghy and Brown, 2015;Lomax et al, 2018;Faghy and Brown, 2019). Lomax et al (2019) found that ΔP imax was not correlated with changes in 100 or 200 m swim times showing that increases in P imax did not determine the magnitude of improvement in performance. Unchanged RMF could be due to potential ineffective training, however in the present study, P imax was increased in EXP when compared to pre-intervention values which was not apparent in CON, indicating training was effective in increasing absolute strength.…”

“…Nevertheless, reductions in FVC (seen both in hypoxia and at reduced ambient temperatures) causes reductions in the volume of air the lungs can support. This increases work of breathing, reduces lung compliance and may lead to RMF (Armstrong et al, 2019). In the present study, the additive effect of both hypoxia and a cold ambient temperature likely led to reduction in FVC and thus P imax .…”

“…RMF reduces exercise tolerance by the activation of the respiratory metaboreflex (Harms et al, 2000). In occupational settings, this could reduce operational time, increase recovery time and reduce overall physical performance (Armstrong et al, 2019). In a recreational setting, this could also negatively impact performance and may increase time to complete an expedition and if prolonged, RMF could negatively impact dyspnea, effort perception and limb discomfort.…”

The incidence of breast health issues and the efficacy of a sports bra fit and issue service in British Army recruits

“…The primary goal of BT is to transform civilians into soldiers. As such, the BT programme is necessarily arduous, involving cyclic high impact loading activities and tasks such as up and downhill running, foot-drill, circuit training, strength training, and marching with external loads of up to 40 kg (Armstrong et al 2019;Chapman et al 2019). Similar cyclic high impact activities involving continuous locomotion and rapid changes in direction are associated with exerciseinduced breast pain in athletic populations, through excessive and repetitive movement in the vertical, medial, and lateral directions (Burbage and Cameron 2017;Mason, Page, and Fallon 1999;White, Scurr, and Smith 2009).…”

A novel fatigue detection method for rehabilitation training of upper limb exoskeleton robot using multi-information fusion

“…In the poststroke rehabilitation process, monitoring of muscle activity is very important to know the developments of muscle strength. Nicola CD Armstrong et al 18 investigated the effect of load carriage on pulmonary function during a treadmill march of increasing intensity. The results of muscle fatigue using surface electromyogram (sEMG) for rehabilitation training system were reported by Liu et al 19 Jannatul Naeem et al 20 proposed the mechanomyography-based muscle fatigue detection during electrically elicited cycling in patients with spinal cord injury; it could be implemented in functional electrical stimulation systems to increase patient safety and to optimize patient training.…”