Robert J. Moffatt

Smoking and smoking cessation-The relationship between cardiovascular disease and lipoprotein metabolism : A review

Cigarette smoking is generally accepted as the most preventable cause of death in the United States today. Individuals who smoke experience a wide range of physiologic side effects that increase the risk of cardiovascular disease (CVD), including insulin resistance, elevated catecholamine levels which contribute to an elevated heart rate and blood pressure, and hypercholesterolemia. The link between hypercholesterolemia and cardiovascular disease has been extensively researched and is undeniable. What is more, this link is strengthened in smokers as cigarette smoking is known to increase total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL), while acting to decrease the cardio-protective high-density lipoprotein (HDL). Alterations in the enzymes that control lipid transport may be a key underlying mechanism contributing to these health destroying effects. This review examines the current literature related to: (1) smoking, lipoproteins, and lipid-related enzymes; (2) the impact of nicotine, carbon monoxide and free radicals on physiologic parameters related to health; and (3) metabolic issues involving smoking cessation and nicotine replacement therapy.

Running Performance Differences Between Men and Women (An Update)

More than a decade ago it was reported in the journal Natures that the slope of improvement in the men’s and women’s running records, extrapolated from mean running velocity plotted against historical time, would eventually result in a performance intersection of the sexes across a variety of running distances. The first of these intersections was to occur for 42 000m before the 21st century. Most of the error in this prediction is probably explained by the linear mathematical treatment and extrapolation of limited performance data, since including world record-setting running performances for women before and after 1985 results in a non-linear data fit. The reality of early, disproportionate improvements in women’s running that gave the appearance of an impending convergence with men is best explained by an historical social sports bias. Women’s times have now reached a plateau similar to that observed for men at comparative performance milestones in the marathon. Sex differences at distances from 100 to 10 000m show similar trends. The remaining sex gaps in performance appear biological in origin. Success in distance running and sprinting is determined largely by aerobic capacity and muscular strength, respectively. Because men possess a larger aerobic capacity and greater muscular strength, the gap in running performances between men and women is unlikely to narrow naturally.

Effects of cessation of smoking on serum lipids and high density lipoprotein-cholesterol

This study examined the effect of cessation of smoking on serum lipid and lipoprotein levels. Twenty-six females who smoked a minimum of 20 cigarettes per day for the past 5 years served as volunteers. Twelve subjects abstained from smoking for a period of 60 days (ex-smokers). Six stopped smoking for 30 days then resumed smoking for an additional 30 days (re-smokers). Eight subjects continued to smoke for the entire 60 days (smokers). Additionally, 10 females who had never smoked served as non-smoking controls (non-smokers). Pre-cessation HDL-C levels for all smoker groups were 15-20% (P less than 0.05) below those of non-smokers. By day 30 of cessation HDL-C levels of ex-smokers and re-smokers significantly increased by 5.7 and 10.5 mg/dl, respectively, and were significantly higher than those of smokers. At day 60, HDL-C of ex-smokers increased another 6.8 mg/dl to 63.9 mg/dl while levels of re-smokers returned to pre-cessation levels (50.7 mg/dl). The findings of this study suggest that low levels of HDL-C associated with smoking in females do not appear to be cumulative and can be reversed in as little as 30 days.

Acute effects of premeal versus postmeal exercise on postprandial hypertriglyceridemia.

ObjectiveThe objective of this study was to examine the effects of the timing of exercise relative to the consumption of a fat-rich meal (81% fat) on postprandial hypertriglyceridemia. DesignA single bout of exercise was either completed 30 minutes before the fat meal (EM trial) or initiated 90 minutes after the fat meal (ME trial). A third trial, fat meal only, served as a control (CON trial). The trials performed in a random order, and venous blood samples were drawn before and 1.5, 3.5, 5.5, and 7.5 hours after the meal for the determination of triglycerides, glycerol, insulin, glucose, and free fatty acids. ParticipantsTen untrained healthy males 25.2 ± 0.9 years old (mean ± SE) with maximal oxygen uptake (VO2max) of 46.6 ± 3.0 mL · kg−1 · min−1. InterventionWalking exercise performed at 50% VO2max for 90 minutes. Main Outcome MeasurePostprandial hypertriglyceridemia, which was quantified by calculating the area under the triglycerides curve over the 7.5-hour postprandial period. ResultsThe mean incremental area under the curve (total area adjusted to baseline) describing postprandial hypertriglyceridemia was lower both in the EM trial (3.16 ± 0.99 mmol · L−1 · 8 h) and in the ME trial (2.96 ± 0.69 mmol · L−1 · 8 h) compared with CON trial (6.18 ± 1.10 mmol · L−1 · 8 h; P < 0.05). The corresponding areas under the curve describing the postprandial insulinemia were not different between trials (ME: 38.56 ± 8.36 uIU · mL−1 · 8 h; EM: 21.65 ± 3.80 uIU · mL−1 · 8 h; CON: 25.06 ± 5.15 uIU · mL−1 · 8 h; P > 0.05). ConclusionA single bout of moderate intensity exercise decreases postprandial hypertriglyceridemia irrespective of the timing of the exercise relative to a high-fat meal.

Influence of water run training on the maintenance of aerobic performance

The purpose of this study was to examine the effect of a 6-wk deep water running program on the maintenance of cardiorespiratory performance (VO2max, ventilatory threshold, running economy); metabolic measurements of blood glucose, blood lactate, and plasma norepinephrine; and body composition. Sixteen trained male runners (VO2max = 58.6 +/- 3.6 ml.kg-1.min-1) were assigned to one of two groups matched by VO2max, treadmill run (R) or water run (WR). Subjects participated in their respective training programs, which consisted of workouts of a) 30 min at 90-100% VO2max and b) 60 min at 70-75% VO2max alternated daily for 5 d.wk-1. Following 6 wk of workouts, no significant intra- or intergroup differences were observed for treadmill VO2max for R (pre = 58.4 +/- 2.3, post = 60.1 +/- 3.6 ml.kg-1.min) and WR (pre = 58.7 +/- 4.7, post = 59.6 +/- 5.4 ml.kg-1.min-1). Similarly, ventilatory threshold was unaltered in R (pre = 47.5 +/- 1.8, post = 48.2 +/- 3.3 ml.kg-1.min-1) and WR (pre = 46.5 +/- 6.4, post = 47.4 +/- 6.7 ml.kg-1.min-1), nor were there any changes in running economy in R (pre = 48.4 +/- 2.3, post = 48.9 +/- 2.0 ml.kg-1.min-1 at 255 m.min-1) and WR (pre = 51.8 +/- 2.0, post = 48.9 +/- 2.2 ml.kg-1.min-1 at 255 m.min-1). No significant differences were observed within or between groups for maximal blood glucose, blood lactate, and plasma norepinephrine concentration as well as for body composition indices. It was concluded that deep water running may serve as an effective training alternative to landbased running for the maintenance of aerobic performance for up to 6 wk in trained endurance athletes.

Acute effects of resistance exercise on parameters of lipoprotein metabolism.

Ten healthy, trained males (25.4 +/- 3.1 yr) were studied before and after 90 min of resistance exercise to determine the acute effects of high volume (HV) and low volume (LV) sessions on alterations in lipid and lipoprotein concentrations as well as the activity of lecithin: cholesterol acyltransferase (LCAT). The HV session involved the use of 8-12 repetition maximum (RM) loads performed to exhaustion with 60 s rest intervals between sets, while the LV session involved the use of 1-5RM loads with 3 min rest intervals between sets. Fasting blood samples were drawn from an antecubital vein immediately before and after exercise as well as 24, 48, and 72 h post-exercise. Following adjustment for changes in plasma volume, significant changes were only found following the HV session. These included increases in HDL-C (11%) and HDL3-C (12%) 24 h post-exercise. Modifications in HDL-C were significantly different from both the LV and control sessions. In contrast, triglycerides and LCAT were significantly depressed 24 h post-exercise following the HV session when compared with immediate post-exercise values. There were no significant changes in either total cholesterol or HDL2-C at any time. The results of this study suggest that the potential of resistance exercise to affect acute modifications in the lipoprotein profile resides in the volume of exercise performed.

Exercise Recovery, Lactate Removal, and Subsequent High Intensity Exercise Performance.

Abstract In order to examine the effects of different recoveries from high intensity short duration exercise on lactate removal and subsequent performance, 11 subjects completed 8 experimental sessions. Each subject completed an initial all-out pedaling task against 5.5 kg resistance (Monark bicycle ergometer) for 1 min followed by a randomly assigned recovery pattern and a repeat of the all-out exercise task. The main effects examined were active (1.0 kg, 60 rpm) vs passive recovery, inhalation of inhalation of oxygen vs room air during recovery, and 10- vs-20-min duration of recovery. Pedal revolutions were analyzed on a 6- by 6-sec and on a cumulative basis. Blood lactate concentrations were determined during rest, the 3rd–4th, 9th–10th, and 19th–20th min of recovery. Results revealed significant main effects for active vs passive recovery and for 10- vs 20-min recovery, with active and 20-min recovery resulting in significantly higher postrecovery pedal revolutions (p < .001) and enhanced rates of lac...

Smoking-induced elevations in blood carboxyhaemoglobin levels. Effect on maximal oxygen uptake.

Many people engage in physical activity to reduce their cardiovascular risk associated with smoking. These people should be made aware of the metabolic and cardiorespiratory changes induced by chronic and acute smoking and, in particular, the exercise ramifications of increased levels of blood carbon monoxide (CO).Smoking-induced elevations in the CO content of the blood can reduce exercise tolerance and maximal aerobic capacity. Smoking also increases the reliance upon glycolytic metabolism during exercise. Together, these factors contribute to earlier fatigue in smokers compared with nonsmokers who exercise. Similar effects upon exercise tolerance are noted in those who inhale environmental tobacco smoke.

Muscular development and lean body weight in body builders and weight lifters

The extent of extreme muscular development in 39 males identified as body builders (N = 18), power weight lifters (N = 13), and Olympic weight lifters (N = 8) were studied. Body composition and anthropometric data, including calculations of pre-excess muscle body weight (scale weight minus excess muscle) were obtained. The lean body weight and percent fats of the subjects were: body builders = 74.6 kg, 9.3%; power weight lifters = 73.3 kg, 9.1%; and Olympic weight lifters = 68.2 kg, 10.8%. No group differences were present in frame size, percent fat, lean body weight, skinfolds, and diameter measurements. The only group differences were for the shoulders, chest, biceps relaxed and flexed, and forearm girths. In each case the body builders were larger. Calculations of excess muscle by the Behnke method revealed that the body builders had 15.6 kg excess muscle, power weight lifters 14.8 kg, and Olympic weight lifters 13.1 kg. Somatographic comparisons revealed only slight differences between the groups, while differences with reference man were substantial.

The effect of smoking on energy expenditure and plasma catecholamine and nicotine levels during light physical activity

A number of studies have found that cigarette smoking causes an acute increase in resting energy expenditure, but the effect on energy expenditure during light physical activity is less clear. Since both smoking and activity have been shown to increase plasma catecholamines, these could produce additive effects on energy expenditure when smoking during light physical activity. In this study, the impact of cigarette smoking on energy expenditure, cardiovascular function, plasma nicotine and plasma catecholamine levels was determined in adult male subjects at rest and while engaged in light physical activity. Smoking at rest resulted in a 3.6% increase in energy expenditure above the resting baseline; whereas the increase in energy expenditure caused by smoking during light physical activity (compared with the light physical activity baseline) was 6.3%. This increase during light physical activity was significantly greater than the increase observed at rest (p < 0.025). As expected, plasma nicotine increased with smoking during both rest and light physical activity. An increase in plasma nicotine was associated with smoking during light physical activity. When this increase was adjusted as a covariate, the difference in smoking-related energy expenditure between light physical activity and rest disappeared, suggesting nicotine accounts for the effect. Plasma epinephrine and norepinephrine levels increased with smoking and showed a significantly greater increase during light physical activity compared to rest. Cigarette smoking caused a significantly greater increase in heart rate during light physical activity than it did while at rest, but there was no significant effect of smoking on mean blood pressure. It was concluded that there is enhanced energy expenditure associated with cigarette smoking during light physical activity when compared with smoking at rest which could be due in part to smoking-induced increases in circulating plasma catecholamines and perhaps nicotine.