Background: Dietary carbohydrate intake has been shown to increase the plasma concentration of tryptophan, a precursor of serotonin and sleep-inducing agent. Objective: To investigate the role of carbohydrate in sleep induction, we explored the effect of glycemic index (GI) and meal time on sleep in healthy volunteers. Design: We compared the effect of high- and low-GI carbohydrate–based meals ingested 4 h before bedtime on sleep quality. We also evaluated the effect of the timing of high-GI meals (4 h compared with 1 h) on sleep quality. Twelve healthy men (aged 18–35 y) were administered standard, isocaloric (3212 kJ; 8% of energy as protein, 1.6% of energy as fat, and 90.4% of energy as carbohydrate) meals of either Mahatma (low GI = 50) or Jasmine (high GI = 109) rice 4 h before their usual bedtime. On another occasion, the high-GI meal was given 1 h before bedtime. The participants underwent a familiarization night followed by 3 test nights in random order 1 wk apart. Results: A significant (P = 0.009) reduction in the mean (±SD) sleep onset latency (SOL) was observed with a high-GI (9.0 ± 6.2 min) compared with a low-GI (17.5 ± 6.2 min) meal consumed 4 h before bedtime. The high-GI meal given 4 h before bedtime showed a significantly shortened SOL compared with the same meal given 1 h before bedtime (9.0 ± 6.2 min compared with 14.6 ± 9.9 min; P = 0.01). No effects on other sleep variables were observed. Conclusions: We showed that a carbohydrate-based high-GI meal resulted in a significant shortening of SOL in healthy sleepers compared with a low-GI meal and was most effective when consumed 4 h before bedtime. The relevance of these findings to persons with sleep disturbance should be determined in future trials.

Dy was to describe training practices and ergogenic aids used by competitive bodybuilders and to determine whether training practices comply with current recommendations for muscular hypertrophy. A web-based survey was completed by 127 competitive male bodybuilders. The results showed that during the off-season phase of training (OFF), the majority of respondents performed 3–6 sets per exercise (95.3%), 7–12 repetition maximum (RM) per set (77.0%), and 61- to 120-seconds recovery between sets and exercises (68.6%). However, training practices changed 6 weeks before competition (PRE), where there was an increased number of respondents who reported undertaking 3–4 sets per exercise at the expense of 5–6 sets per exercise (p < 0.001), an increase in the number reporting 10–15RM per set from 7–9RM per set (p < 0.001), and an increase in the number reporting 30–60 seconds vs. 61–180 seconds recovery between sets and exercises (p < 0.001). Anabolic steroid use was high among respondents competing in amateur competitions (56 of 73 respondents), whereas dietary supplementation was used by all respondents. The findings of this study demonstrate that competitive bodybuilders comply with current resistance exercise recommendations for muscular hypertrophy; however, these changed before competition during which there is a reduction resistance training volume and intensity. This alteration, in addition to an increase in aerobic exercise volume, is purportedly used to increase muscle definition. However, these practices may increase the risk of muscle mass loss in natural compared with amateur bodybuilders who reportedly use drugs known to preserve muscle mass....

During resistance exercise, a brief Valsalva maneuver (VM) is unavoidable when lifting heavy loads (>80% of maximal voluntary contraction) or when lifting lighter loads to failure. It has been proposed that the performance of the VM during resistance exercise increases the stability of the spine because of augmented intra-abdominal pressure (IAP). However, resistance trainers are often advised to avoid the VM during resistance exercise because of potential adverse vascular events. The aim of this review was to establish the effect of the VM on IAP and to evaluate if the VM during resistance exercise is a safe practice. Relevant databases were searched to examine the effect of the VM on: (a) IAP and (b) hemodynamics during resistance exercise and reported adverse events. The data show that the VM alone increases IAP and that the VM augment IAP during various resistance exercises. An incremental rise in IAP was observed as the lifting intensity and effort increased, with IAP tending to be lower compared with peak IAP from the VM alone. The VM was associated with an increase in blood pressure during resistance exercise, but the VM alone was associated with greater hemodynamic changes. In conclusion, the VM effectively increases IAP, which may assist with spine stability and trunk rigidity during resistance exercise. The health risks associated with the VM during resistance exercise remain unconfirmed.

We compared the effect of short-term consumption of a very low carbohydrate (VLC) diet over 48 h to a control mixed diet on sleep indices in healthy, non-obese men. This study employed a repeated-measure design where subjects were given isocaloric (2400 kcal) diets and matching evening test meals (4 h before usual bed-time), which were either mixed low-fat, high carbohydrate (15.5%, 12.5% and 72% of energy from protein, fat and carbohydrate, respectively) or VLC (38%, 61% and < 1% of energy from protein, fat and carbohydrate, respectively). Polysomnographic testing was performed on the familiarization and control night, 4 h after the first VLC test meal (acute phase) and 48 h (ketosis phase) following commencement of the VLC diet. Fourteen healthy, non-obese men (aged 18-35 years; body mass index 23.4 +/- 1.9 kg/m(2)) who were good sleepers took part in the study. Objective sleep was recorded using a computerized sleep system. Urine ketone level was monitored with reagent strips before the evening test meals and at bed-time on the control night, during the VLC acute and ketosis phases. Blood glucose level was measured with a glucometer before the evening test meal until 120 min following the meal. Hunger and fullness were assessed immediately after the meal until bed-time with Likert scales. The proportion of rapid-eye movement (REM) sleep to total sleep time was significantly reduced at the VLC acute and VLC ketosis when compared to the control night (P = 0.006; n = 11 and P = 0.05; n = 14, respectively). The percentage of slow wave sleep (SWS) significantly increased for both the VLC acute (17.7 +/- 6.7) and ketosis (17.8 +/- 6.1) phases compared to control (13.9 +/- 6.3), P = 0.02 for both phases. In healthy, good sleepers, the VLC diet over the short-term promotes increases in the percentage of SWS (deep sleep stage 4) and a reduction in the percentage of REM sleep ('dreaming' sleep) compared to the control mixed diet. The sleep changes may be linked to the metabolism of the fat content of the VLC diet.