Effects of Easy-to-Use Protein-Rich Energy Bar on Energy Balance, Physical Activity and Performance during 8 Days of Sustained Physical Exertion

Abstract

BackgroundPrevious military studies have shown an energy deficit during a strenuous field training course (TC). This study aimed to determine the effects of energy bar supplementation on energy balance, physical activity (PA), physical performance and well-being and to evaluate ad libitum fluid intake during wintertime 8-day strenuous TC.MethodsTwenty-six men (age 20±1 yr.) were randomly divided into two groups: The control group (n = 12) had traditional field rations and the experimental (Ebar) group (n = 14) field rations plus energy bars of 4.1 MJ•day−1. Energy (EI) and water intake was recorded. Fat-free mass and water loss were measured with deuterium dilution and elimination, respectively. The energy expenditure was calculated using the intake/balance method and energy availability as (EI/estimated basal metabolic rate). PA was monitored using an accelerometer. Physical performance was measured and questionnaires of upper respiratory tract infections (URTI), hunger and mood state were recorded before, during and after TC.ResultsEbar had a higher EI and energy availability than the controls. However, decreases in body mass and fat mass were similar in both groups representing an energy deficit. No differences were observed between the groups in PA, water balance, URTI symptoms and changes in physical performance and fat-free mass. Ebar felt less hunger after TC than the controls and they had improved positive mood state during the latter part of TC while controls did not. Water deficit associated to higher PA. Furthermore, URTI symptoms and negative mood state associated negatively with energy availability and PA.ConclusionAn easy-to-use protein-rich energy bars did not prevent energy deficit nor influence PA during an 8-day TC. The high content of protein in the bars might have induced satiation decreasing energy intake from field rations. PA and energy intake seems to be primarily affected by other factors than energy supplementation such as mood state.

No effect of increasing protein intake during military exercise with severe energy deficit on body composition and performance

“…Surprisingly, FFM remained unchanged from pre‐ to post‐exercise in both groups. This contradicts most previous studies, though it is supported by others, a discrepancy that may be related to considerable variations in study design, including varying degrees of energy deficiency . It is important to note that in the present study, FFM measurements were associated with methodological uncertainty connected to the timing of post‐exercise scanning as discussed in a later paragraph.…”

“…The severe level of energy deficiency experienced by the soldiers may explain the lack of beneficial effects of higher protein ingestion on performance, giving support to some studies, but contrasting other studies in soldiers and athletes undergoing weight loss . The resulting catabolic physiological environment may have counteracted anabolic signaling events, which arguably was more pronounced in HIGH, caused by the likely higher amino acid availability from exogenous protein intake.…”

“…Soldiers participating in military field exercises or warfare often operate in a state of energy deficit in a demanding environment, with little opportunity for rest, recovery, and nutritional intake . The energy imbalance typically leads to a catabolic physiological state, accompanied by alterations in body composition, including loss of overall body mass, lean body mass (LBM), and fat mass . The catabolic state is characterized by disturbances in endocrine functions, including reduced circulating levels of anabolic hormones such as testosterone (TESTO) and insulin‐like growth factor 1 (IGF‐1), and increased levels of catabolic hormones such as cortisol (COR), which correlate well with observed losses in muscle mass during military exercises of both short and long duration.…”

“…In line with this, selected studies suggest that increased protein intake attenuates LBM loss during military exercises (2.0‐2.3 g kg −1 d −1 vs 1.5‐1.6 g kg −1 d −1 ) . In these studies, surplus protein was ingested as an addition to the regular diet, essentially meaning that the total energy intake was higher in protein‐ingesting subjects than in control subjects . Hence, they did not investigate the effect of protein supplement on muscle mass and performance per se , as energy availability is a potent modulator of these variables .…”

A review of the physiological and psychological health and wellbeing of naval service personnel and the modalities used for monitoring

“…These instruments may not be suitable for repeated use with large groups because the equipment is expensive, however; they are frequently used in the field by physiologists. The instruments, specifically the contact mat and force plates, have been used to measure the squat and counter movement jumps (CMJ) [114, 118]. Experts also use common field tests, which do not require expensive equipment, and include the Sargent vertical jump test [119] and the standing long jump [120].…”