Energy expenditure of genuine laughter.

OBJECTIVE: To measure energy expenditure (EE) and heart rate (HR) during genuine laughter. DESIGN: Experimental trial of viewing film clips in four cycles either intended to evoke laughter (humorous -10 min) or unlikely to elicit laughter (not humorous -5 min) under strictly controlled conditions of a whole-room indirect calorimeter equipped with audio recording system. PARTICIPANTS: Forty five adult friend dyads in either same-sex male (n=7), same-sex female (n=21) and mix-sex male-female (n=17); age 18-34 years; body mass index 24.7+/-4.9 (range 17.9-41.1). MEASUREMENTS: Energy expenditure in a whole-room indirect calorimeter, HR using Polar HR monitor. Laugh rate, duration and type from digitized audio data using a computerized system and synchronized with HR and EE results. RESULTS: Laughter EE was 0.79+/-1.30 kJ/min (0.19+/-0.31 kcal/min) higher than resting EE (P<0.001, 95% confidence interval=0.75-0.88 kJ/min), ranging from -2.52 to 9.67 kJ/min (-0.60-2.31 kcal/min). Heart rate during laughter segments increased above resting by 2.1+/-3.8 beats/min, ranging from -7.6 to 26.8 beats/min. Laughter EE was correlated with HR (r (s)=0.250, P<0.01). Both laughter EE and HR were positively correlated with laughter duration (r (s)=0.282 and 0.337, both P<0.001) and rate (r(s)=0.256 and 0.298, both P<0.001). CONCLUSION: Genuine voiced laughter causes a 10­20% increase in EE and HR above resting values, which means that 10­15 minutes of laughter per day could increase total EE by 10­40 kJ (2­10 kcal) [corrected].

Insulin resistance is associated with skeletal muscle protein breakdown in non-diabetic chronic hemodialysis patients.

Deranged protein metabolism is known to complicate uremia. Insulin resistance is evident in chronic hemodialysis (CHD) patients. We hypothesized that the degree of insulin resistance would predict protein catabolism in non-diabetic CHD patients. We examined the relationship between Homeostasis Model Assessment (HOMA) and fasting whole-body and skeletal muscle protein turnover in 18 non-diabetic CHD patients using primed-constant infusions of L-(1-(13)C) leucine and L-(ring-(2)H(5)) phenylalanine. Mean+/-s.d. fasting glucose and body mass index were 80.6+/-9.8 mg/dl and 25.4+/-4.4 kg/m(2), respectively. Median (interquartile range) HOMA was 1.6 (1.4, 3.9). Mean+/-s.e.m. skeletal muscle protein synthesis, breakdown, and net balance were 89.57+/-11.67, 97.02+/-13.3, and -7.44+/-7.14 microg/100 ml/min, respectively. Using linear regression, a positive correlation was observed between HOMA and skeletal muscle protein synthesis (R(2)=0.28; P=0.024), and breakdown (R(2)=0.49; P=0.001). An inverse association between net skeletal muscle protein balance and HOMA was also noted (R(2)=0.20; P=0.066). After adjustment for C-reactive protein, only the relationship between HOMA and skeletal muscle protein breakdown persisted (R(2)=0.49; P=0.006). There were no significant associations between components of whole-body protein turnover and HOMA. This study demonstrates that insulin resistance is evident in non-diabetic dialysis patients, is associated with skeletal muscle protein breakdown, and represents a novel target for intervention in uremic wasting.

Protein and energy depletion in chronic hemodialysis patients: clinical applicability of diagnostic tools.

Protein and energy depletion states are common and associated with increased morbidity and mortality in chronic hemodialysis (CHD) patients. Therefore, proper use of diagnostic tools to assess depleted states in CHD patients is critical. Assessment of protein and energy status can be done by an array of methodologies that include simple estimates of the visceral and somatic pools of protein to more refined techniques to measure protein and energy balance. The nutritional and metabolic derangements in the CHD population are highly complex and can be confounded by multiple comorbidities and fluid shifts between body compartments. Therefore, assessment of protein and energy status in CHD patients requires a wide range of methodologies that not only identify depleted states but also monitor nutrition therapy and predict clinical outcome. Most important, these methods require cautious and individualized interpretation in order to minimize the interference of comorbid conditions frequently observed in the CHD population. Currently, there is not a single method that can be considered the gold standard for assessment of protein and energy status in CHD patients. Therefore, a combination of methods is recommended. In this review, we describe available methods to assess protein and energy status, with special considerations pertaining to CHD patients.

Patterns of physical activity in free-living adults in the Southern United States.

OBJECTIVE: To examine the relationship between the amount and patterns of physical activity (PA), body fatness, and age in a heterogeneous adult population in the free living. DESIGN: Cross-sectional study of the amount of PA over a 1-week period. The amount of body movements during PA (PA counts*10(3)) and time spent on various PA intensity categories were calculated from a triaxial accelerometer and compared with subject characteristics, including body fat from hydrodensitometry. PARTICIPANTS: Adult healthy men (n=48) and women (n=72) were recruited from the Nashville, Tennessee area and their PA was monitored in their free-living environment. RESULTS: The average weekday PA counts (176.5+/-60.3, P=0.002, r(2)=0.294), PA counts day-to-day variability (47.3+/-32.7, P=0.002, r(2)=0.286), daily maximum PA counts (241.9+/-89.2, P=0.001, r(2)=0.327), minute-to-minute variability on weekdays (0.281+/-0.091, P=0.001, r(2)=0.362), and the difference between maximum and minimum daily PA counts (130.6+/-78.3, P=0.008, r(2)=0.243) were significantly and negatively correlated with body fatness. During awake time, both men and women spent 10-12 h on low intensity (1.0-2.9 metabolic equivalents (METs)) PA, approximately 1 h on moderate (3.0-5.9 MET), and less than 10 min on vigorous (>6.0 MET) PA each day. On weekends, men and women spent more time at rest (1 MET), less time on low-intensity PA, and men spent more time on moderate PA than on weekdays. CONCLUSIONS: In adults living in the Southern US the amount of free-living PA was negatively correlated with body fatness. Both men and women spent the majority of active time on low and moderate PA. PA patterns on weekends were different than on weekdays and were related to sex and age, but not to body fatness. SPONSORSHIP: National Institutes of Health, US.