Effect of increased dietary protein on tolerance to intensified training.
ABSTRACT The purpose of the present study was to examine the effect of increased protein intake on short-term decrements in endurance performance during a block of high-intensity training.
Trained male cyclists (VO(2max) = 64.2 ± 6.5 mL·kg(-1)·min(-1)) completed two 3-wk trials both divided equally into normal (NOR), intensified (INT), and recovery (REC) training. In a counterbalanced crossover experimental design, cyclists received either a high-protein (PRO; 3 g protein·kg(-1) body mass (BM)·d(-1)) or a normal diet (CON; 1.5 g protein·kg(-1) BM·d(-1)) during INT and REC. Dietary carbohydrate content remained constant at 6 g·kg(-1) BM·d(-1). Energy balance was maintained during each training week. Endurance performance was assessed with a VO(2max) test and a preloaded time trial. Alterations in blood metabolite responses to exercise were measured at rest, during, and after exercise. Cyclists completed the Daily Analysis of Life Demands for Athletes (DALDA) questionnaire each day.
Increased dietary protein intake led to a possible attenuation (4.3%; 90% confidence limits ×/÷5.4%) in the decrement in time trial performance after a block of high-intensity training compared with NOR (PRO = 2639 ± 350 s; CON = 2555 ± 313 s). Restoration of endurance performance during recovery training possibly benefited (2.0%; ×/÷4.9%) from additional protein intake. Frequency of symptoms of stress described as "worse than normal" reported after a block of high-intensity training was very likely (97%) attenuated (17; ±11 AUC of "a" scores part B, DALDA for INT + REC) by increasing the protein content of the diet. No discernable changes in blood metabolite concentrations were observed in PRO.
Additional protein intake reduced symptoms of psychological stress and may result in a worthwhile amelioration of the performance decline experienced during a block of high-intensity training.
Article: Effects of Easy-to-Use Protein-Rich Energy Bar on Energy Balance, Physical Activity and Performance during 8 Days of Sustained Physical Exertion.[show abstract] [hide abstract]
ABSTRACT: Previous 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. Twenty-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. Ebar 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. An 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.PLoS ONE 01/2012; 7(10):e47771. · 4.09 Impact Factor
[show abstract] [hide abstract]
ABSTRACT: We examined whether exercise-induced lymphocytosis and lymphocytopenia are impaired with high-intensity training. Eight trained cyclists (VO(2max) = 64.2 ± 6.5 mL · kg(-1) · min(-1)) undertook 1 wk of normal-intensity training and a second week of high-intensity training. On day 7 of each week, participants performed a cycling task, consisting of 120 min of submaximal exercise followed by a 45-min time trial. Blood was collected before, during, and after exercise. CD8(+) T lymphocytes (CD8(+)TLs) were identified, as well as CD8(+)TL subpopulations on the basis of CD45RA and CD27 expression. High-intensity training (18,577 ± 10,984 cells per microliter × ~165 min) was associated with a smaller exercise-induced mobilization of CD8(+)TLs compared with normal-intensity training (28,473 ± 16,163 cells per microliter × ~165 min, P = 0.09). The response of highly cytotoxic CD8(+)TLs (CD45RA(+)CD27(-)) to exercise was smaller after 1 wk of high-intensity training (3144 ± 924 cells per microliter × ~165 min) compared with normal-intensity training (6417 ± 2143 cells per microliter × ~165 min, P < 0.05). High-intensity training reduced postexercise CD8(+)TL lymphocytopenia (-436 ± 234 cells per microliter) compared with normal-intensity training (-630 ± 320 cells per microliter, P < 0.05). This was driven by a reduced egress of naive CD8(+)TLs (CD27(+)CD45RA(+)). High-intensity training was associated with reduced plasma epinephrine (-37%) and cortisol (-15%) responses (P < 0.05). High-intensity training impaired CD8(+)TL mobilization and egress in response to exercise. Highly cytotoxic CD8(+)TLs were primarily responsible for the reduced mobilization of CD8(+)TLs, which occurred in parallel with smaller neuroendocrine responses. The reduced capacity for CD8(+)TLs to leave blood after exercise with high-intensity training was accounted for primarily by naive, and also, highly cytotoxic CD8(+)TLs. This impaired CD8(+)TL redistribution in athletes undertaking intensified training may imply reduced immune surveillance.Medicine and science in sports and exercise 04/2012; 44(9):1689-97. · 3.71 Impact Factor