G. G. Rogers

High nocturnal body temperatures and disturbed sleep in women with primary dysmenorrhea

Primary dysmenorrhea is characterized by painful uterine cramps, near and during menstruation, that have an impact on personal life and productivity. The effect on sleep of this recurring pain has not been established. We compared sleep, nocturnal body temperatures, and hormone profiles during the menstrual cycle of 10 young women who suffered from primary dysmenorrhea, without any menstrual-associated mood disturbances, and 8 women who had normal menstrual cycles. Dysmenorrheic pain significantly decreased subjective sleep quality, sleep efficiency, and rapid eye movement (REM) sleep but not slow wave sleep (SWS), compared with pain-free phases of the menstrual cycle and compared with the controls. Even before menstruation, in the absence of pain, the women with dysmenorrhea had different sleep patterns, nocturnal body temperatures, and hormone levels compared with the controls. In the mid-follicular, mid-luteal, and menstrual phases, the dysmenorrheics had elevated morning estrogen concentrations, higher mean in-bed temperatures, and less REM sleep compared with the controls, as well as higher luteal phase prolactin levels. Both groups of women had less REM sleep when their body temperatures were high during the luteal and menstrual phases, implying that REM sleep is sensitive to elevated body temperatures. We have shown that dysmenorrhea is not only a disorder of menstruation but is manifest throughout the menstrual cycle. Furthermore, dysmenorrheic pain disturbs sleep, which may exacerbate the effect of the pain on daytime functioning.

Acute appetite reduction associated with an increased frequency of eating in obese males

OBJECTIVE: To investigate the effects of altered feeding frequencies on the relationship between perceived hunger and subsequent food intake and appetite control in obese men.DESIGN: Obese men reported in a fasted state in the morning to the laboratory where an isoenergetic pre-load (4100±234 kJ, which was 33% average daily energy requirement (ADER) of each subject) comprising 70% carbohydrate, 15% protein, and 15% fat was given. This was administered either as a SINGLE meal, or divided evenly over 5 meals given hourly as a MULTI feeding pattern. Five hours after the first pre-load, an ad libitum test meal was given to determine whether there was a difference in the amount of energy that was consumed between the two eating patterns.SUBJECTS: Seven non-diabetic, non-smoking, unrestrained obese men (age 37.4±18.5; BMI 40.02±10.93 kg/m−2) were recruited for this study. Subjects were not told the precise reasons for this study but rather were informed that changes in blood glucose, insulin and free fatty acids with meal frequency were to be monitored.MEASUREMENTS: Blood glucose, serum insulin and free fatty acid (FFA) concentrations, and visual analogue scales (VAS) were measured prior to commencing the feeding regime and thereafter hourly for 5 h. Thereafter an ad libitum meal was given. The weight (and energy content) of the food consumed, and the time taken to eat lunch were recorded. Following this ad libitum lunch, the same variables were determined again (15, 45, and 75 min post-test meal).RESULTS: When given a SINGLE pre-load, 27% more (t=2.651; P<0.05) energy was consumed in the ad libitum test meal (5261±1289 kJ) compared to that eaten after the MULTI pre-load (3763±1986 kJ). This increase in food intake occurred despite no significant change in subjective hunger ratings. Over the 315 min pre-load period, peak insulin concentrations were significantly higher (F6,72=7.95, P<0.01) on the SINGLE treatment (171.2±129.8 μU ml−1) than on the MULTI treatment (133.7±70.2 μU ml−1). Serum insulin remained elevated for longer on the MULTI meal treatment, resulting in no difference in the area under the insulin curves between the two feeding treatments. There was a positive correlation (r=0.87) between the amount of energy consumed at lunch and insulin concentration before lunch in the SINGLE group. However, this relationship was not apparent when subjects were given the MULTI meal preload.CONCLUSION: Obese males fed an isoenergetic pre-load sub-divided into a multi-meal plan consumed 27% less at a subsequent ad libitum test meal than did the same men when given the pre-load as a single meal. Prolonged but attenuated increases in serum insulin concentration on the multi-meal programme may facilitate this acute reduction in appetite.

Water budget during ultra-endurance exercise

We examined water gains and water losses in a group of athletes after an ultra-endurance event. Thirteen male triathletes competed in a triathlon consisting of 21 km canoeing, 97 km cycling, and 42 km running. Water loss determinations included sweat rate (940 +/- 163 g.h-1), urine output (41 +/- 38 g.h-1), and respiratory water loss (88 +/- 10 g.h-1). Water gain measurements included water intake (737 +/- 137 g.h-1) and the water content of the food intake (10 +/- 7 g.h-1), and we estimated the water of metabolism for carbohydrate (49 +/- 5 g.h-1) and fat (41 +/- 5 g.h-1) and the water released after glycogen utilization (104 +/- 64 g.h-1). Total water gain averaged 940 +/- 160 g.h-1, while the total water loss averaged 1069 +/- 163 g.h-1. Body weight changed from 69.87 +/- 7.14 kg before the race to 66.65 +/- 6.75 kg after the race (-4.61 +/- 2.94%). The sum of the exogenous water gains and the endogenous water gains (940 g.h-1) replaced almost 90% of the total water loss (1069 g.h-1). The difference (1334 g) represented a loss of about 1.9% of the initial body mass (69.87 kg). The exogenous water gains alone (747 g.h-1) replaced about 70% of the total water loss, and the difference represented a loss of over 4% of the initial body mass. Because of the nature of the endogenous sources of water gain, the total amount of water gain almost replaces the total amount of water loss (difference approximately 12%) even in the presence of a reduction in body mass (> 4%).

Effects of training volume on sleep, psychological, and selected physiological profiles of elite female swimmers

Excessive training is reported to cause sleep disturbances and mood changes. We examined sleep and psychological changes in female swimmers across a competitive swimming season, that is, at the start of the season (onset), during peak training period (peak), and after a precompetition reduction in training (taper). For each phase, polysomnographic recordings, body composition, psychological parameters, and swimming performance were obtained. A daily training log and sleep diary were maintained for the entire study period. Sleep onset latency (SOL) time awake after sleep onset, total sleep time (TST), and rapid eye movement (REM) sleep times were similar at all three training levels. Slow wave sleep (SWS) formed a very high percentage of total sleep in the onset (26%) and peak (31%) training periods, but was significantly reduced following precompetition taper (16%), supporting the theory that the need for restorative SWS is reduced with reduced physical demand. The number of movements during sleep was significantly higher at the higher training volumes, suggesting some sleep disruption. In contrast to other studies, mood deteriorated with a reduction in training volume and/or impending competition.

Differences in ultra-endurance exercise in performance-matched male and female runners.

Our study investigated endurance performances in a performance-matched (running 42.2 km) group of females (N = 10) and males (N = 10). The distances examined were 10 km, 21.1 km, 42.2 km, and 90 km. Measurements included VO2max, running economy, lactate accumulation, and running speeds. Although our female subjects performed as well as their male counterparts at 42.2 km (194.8 +/- 12.9 m.min-1 vs 192.6 +/- 16.3 m.min-1), the performance for 90 km was significantly better (P < 0.05) in the female group (171.0 +/- 11.7 m.min-1 vs 155.2 +/- 14.7 m.min-1). The average fraction of the VO2max (F) sustained by each subject indicated that the females achieved their performances by working at a higher (P < 0.01) F (73.4 +/- 5.5% vs 66.3 +/- 3.7% for 42.2 km and 59.8 +/- 6.2% vs 50.2 +/- 3.1% for 90 km). The degree of decline in the fraction of the VO2max sustained as the distance of running increased was significantly less (P < 0.05) in the females. The better performance by the females at 90 km was not related to greater maximal aerobic capacity, running economy, training level, or fatty acid metabolism.

The response of runners to arduous triathlon competition

SummaryAs very few of the competitors in a triathlon are truly specialist in more than one of the three disciplines, high levels of physical (and mental) stress may result during the course of the event. We investigated some of the physiological responses occurring in runners participating in an “Iron Man” triathlon consisting of canoeing (20 km), cycling (90 km) and running (42 km), in that sequence.Twenty-one male entrants volunteered as subjects for the study. Prior to the competition, maximal oxygen consumption (

An evaluation of exercise cardiac output using the CO2 rebreathing extrapolation technique.

\dot V_{{\text{O}}_{{\text{2max}}} }

Frequency responses of infant air-balloon versus liquid-filled catheters for intra-esophageal pressure measurement

) was determined. Basal venous blood samples were collected on the day prior to the competition and post-exercise venous blood samples were collected within 5 minutes of completion of the race.Serum iron was significantly reduced from a mean basal value of 20.6 Μmol · l−1 to a mean value of 8.4 Μmol · l−1 after the race. Cortisol levels showed a 3 fold increase after the race. Gross