Gerald S. Zavorsky

Randomized clinical trial of prehabilitation in colorectal surgery

‘Prehabilitation’ is an intervention to enhance functional capacity in anticipation of a forthcoming physiological stressor. In patients scheduled for colorectal surgery, the extent to which a structured prehabilitation regimen of stationary cycling and strengthening optimized recovery of functional walking capacity after surgery was compared with a simpler regimen of walking and breathing exercises.

Optimizing functional exercise capacity in the elderly surgical population

Purpose of reviewThere are several studies on the effect of exercise post surgery (rehabilitation), but few studies have looked at augmenting functional capacity prior to surgical admission (prehabilitation). A programme of prehabilitation is proposed in order to enhance functional exercise capacity in elderly patients with the intent to minimize the postoperative morbidity and accelerate postsurgical recovery. Recent findingsFew studies have looked at exercise prehabilitation to improve functional capacity prior to surgical admission. Prehabilitation prior to orthopaedic surgery does not seem to improve quality of life or recovery. However, prehabilitation prior to abdominal or cardiac surgery, based on 275 elderly patients, results in fewer postoperative complications, shorter postoperative length of stay, improved quality of life, and reduced declines in functional disability compared to sedentary controls. SummaryA concentrated 3-month progressive exercise prehabilitation programme consisting of aerobic training at 45-65% of maximal heart rate reserve (%HRR) along with periodic high-intensity interval training (∼90% HRR) four times per week, 30-50 minutes per session, is recommended for improving cardiovascular functioning. A strength training programme of about 10 different exercises focused on large, multi-jointed muscle groups should also be implemented twice per week at a mean training intensity of 80% of one-repetition maximum. Finally, a minimum of 140 g (∼560 kcal) of carbohydrate (CHO) should be taken 3 h before training to increase liver and muscle glycogen stores and a minimum of about 200 kcal of mixed protein-CHO should be ingested within 30 min following training to enhance muscle hypertrophy.

Arterial versus capillary blood gases: a meta-analysis.

A meta-analysis determined whether capillary blood gases accurately reflect arterial blood samples. A mixed effects model was used on 29 relevant studies obtained from a PubMed/Medline search. From 664 and 222 paired samples obtained from the earlobe and fingertip, respectively, earlobe compared to fingertip sampling shows that the standard deviation of the difference is about 2.5x less (or the precision is 2.5x better) in resembling arterial PO(2) over a wide range of arterial PO(2)s (21-155 mm Hg ). The lower the arterial PO(2), the more accurate it is when predicting arterial PO(2) from any capillary sample (p<0.05). However, while earlobe sampling predicts arterial PO(2) (adjusted r(2)=0.88, mean bias=3.8 mm Hg compared to arterial), fingertip sampling does not (adjusted r(2)=0.48, mean bias=11.5 mm Hg compared to arterial). Earlobe sampling is slightly more accurate compared to fingertip sampling in resembling arterial PCO(2) (arterial versus earlobe, adjusted r(2)=0.94, mean bias=1.9 mm Hg ; arterial versus fingertip, adjusted r(2)=0.95, mean bias=2.2 mm Hg compared to arterial) but both sites can closely reflect arterial PCO(2) (880 total paired samples, range 10-114 mm Hg ). No real difference between sampling from the earlobe or fingertip were found for pH as both sites accurately reflect arterial pH over a wide range of pH (587 total paired samples, range 6.77-7.74, adjusted r(2)=0.90-0.94, mean bias=0.02). In conclusion, sampling blood from the fingertip or earlobe (preferably) accurately reflects arterial PCO(2) and pH over a wide range of values. Sampling blood, too, from earlobe (but never the fingertip) may be appropriate as a replacement for arterial PO(2), unless precision is required as the residual standard error is 6 mm Hg when predicting arterial PO(2) from an earlobe capillary sample.

Pulmonary gas exchange in the morbidly obese

The literature on pulmonary gas exchange at rest, during exercise, and with weight loss in the morbidly obese (body mass index or BMI ≥ 40 kg m−2) is reviewed. Forty‐one studies were found (768 subjects weighted mean = 40 years old, BMI = 48 kg m−2). The alveolar‐to‐arterial oxygen partial pressure difference (AaDO2) was large at rest in upright subjects at sea level (23, range 5–38 mmHg) while the arterial pressure of oxygen (PaO2) was low (81, range 50–95 mmHg). Arterial pressure of carbon dioxide (PaCO2) was normal. At peak exercise (162 W), gas exchange improves. Weight loss of 45 kg (BMI = −13 kg m−2) over 18 months is associated with an improvement in PaO2 (by 10 mmHg, range 1–23 mmHg), a reduction in AaDO2 (by 8 mmHg, range −3 to −16 mmHg), and PaCO2 (by −3 mmHg, range 3 to −14 mmHg) at rest. Every 5–6 kg reduction in weight increases PaO2 by 1 and reduces AaDO2 by 1 mmHg, respectively. Morbidly obese women have better gas exchange at rest compared with morbidly obese men which is likely due to lower waist‐to‐hip ratios in women than from differences in weight or BMI.

An open-label dose–response study of lymphocyte glutathione levels in healthy men and women receiving pressurized whey protein isolate supplements

Background High-pressure treatment of whey protein may increase digestibility and bioavailability of cysteine. The purpose of the study was to determine whether total lymphocyte glutathione (γ-glutamyl-cysteinyl-glycine [GSH]) levels (oxidized+reduced) can be augmented from three different doses of pressurized whey protein supplements in a dose-dependent manner over a 2-week period. Methods Eighteen healthy males and 18 healthy females were randomized into three different groups, with 31 finishing the study. Each group ingested 15, 30, or 45 g/day pressurized whey protein in the morning in bar format for 14 days. Each group was blinded to the amount of whey protein they were ingesting. Ten millilitres of blood was withdrawn before and after the 2-week period to assess blood lymphocyte levels pre and post supplementation. Results There was no change in body weight or reported physical activity levels pre and post supplementation. Pre-lymphocyte GSH levels were not significantly different between groups (3.7±0.7µmol/l). Least-squares linear regression showed that the change in lymphocyte GSH levels from pre to post supplementation was affected by the amount of whey protein ingested daily (P=0.037). The group that ingested 45 g/day pressurized whey protein augmented GSH levels the most (by ∼24%), and the group that ingested 15 g/day did not increase lymphocyte GSH levels. Conclusions We conclude that there is a significant relationship between the dosage of supplementation and the change in lymphocyte GSH levels. Furthermore, the increase in GSH was linear with the amount of whey protein ingested. Pressurized whey protein supplementation of 45 g/day for 2 weeks can increase lymphocyte GSH by 24%.

Radiographic evidence of pulmonary edema during high-intensity interval training in women

The purpose was to determine if an intense interval training session could produce transient pulmonary edema in women. Fourteen females [(27+/-4 years; body mass index of 21.6+/-1.5 kg/m(2)); maximal oxygen consumption = 3.12+/-0.42 L/min] performed three sets of 5 min sea-level cycling exercise with 10-min recovery between each set. Average oxygen consumption at minute 5 of each set was 96+/-5% of maximum and arterial plasma lactate concentration at minute 5 of each set was 16.0+/-3.3 mmol/L. Chest radiographs were obtained before and 33.2+/-6.1 min after exercise. Four different chest radiologists independently reviewed the radiographs for edema, and scored seven validated radiographic characteristics on a three-point scale (0-2). The overall edema score increased from 1.3+/-1.6 before exercise to 1.9+/-2.0 after exercise [P<0.05; Delta = +0.7+/-1.8, 95% CI, 0.2 to +1.1]. This study shows that an intense interval training session can cause mild, detectable pulmonary edema in some women.

Acute effects of intense interval training on running mechanics

The aims of this study were to determine if there are significant kinematic changes in running pattern after intense interval workouts, whether duration of recovery affects running kinematics, and whether changes in running economy are related to changes in running kinematics. Seven highly trained male endurance runners (VO 2max = 72.3 +/- 3.3 ml kg -1 min -1 ; mean +/- s) performed three interval running workouts of 10 X 400 m at a speed of 5.94 +/- 0.19 m s -1 (356 +/- 11.2 m min -1 ) with a minimum of 4 days recovery between runs. Recovery of 60, 120 or 180 s between each 400 m repetition was assigned at random. Before and after each workout, running economy and several kinematic variables were measured at speeds of 3.33 and 4.47 m s -1 (200 and 268 m min -1 ). Speed was found to have a significant effect on shank angle, knee velocity and stride length (P ≪ 0.05). Correlations between changes pre- and post-test for VO 2 (ml kg -1 min -1 ) and several kinematic variables were not significant (P > 0.05) at both speeds. In general, duration of recovery was not found to adversely affect running economy or the kinematic variables assessed, possibly because of intra-individual adaptations to fatigue.

Comparison of fingertip to arterial blood samples at rest and during exercise.

Objective:The purpose was to determine whether arterialized fingertip blood-gas samples are comparable to arterial samples at rest and at exercise. Design:Repeated measures, with subjects serving as their own controls. Setting:Department of Anesthesia, Montreal General Hospital, Montreal, Quebec, Canada, (January to April 2004). Participants:Fifteen healthy men (age = 25 ± 4 y; weight = 76.4 ± 11.4 kg; height = 180.7 ± 8.0 cm; peak oxygen uptake or &OV0312;O2peak = 46.0 ± 9.0 mL · kg−1 · min−1). Main outcome measures:Arterial blood gases, metabolites, electrolytes. Results:Blood sampled simultaneously from the radial artery and warmed fingertip at rest and during 2 levels of exercise (vigorous 181 W or 70% &OV0312;O2peak; maximal 261 W or 100% &OV0312;O2peak) on a electronically braked ergometer. Arterial partial pressure of oxygen in blood combining rest and the 2 exercise levels was on average 13.6 ± 9.0 mm Hg higher than arterialized fingertip samples, with the largest difference occurring at rest (18.8 ± 6.5 mm Hg; 95% CI = 15.5, 22.1) and the smallest difference occurring at the highest level of exercise (8.3 ± 9.2 mm Hg; 95% CI = 3.6, 13.0; P < 0.05). The pattern for oxyhemoglobin saturation was the same, showing statistical differences between the sampling sites with the differences reduced at the highest exercise intensity. In contrast, there was no difference in arterial and arterialized partial pressure of carbon dioxide in blood (−1.0 ± 1.5 mm Hg; 95% CI = −1.4, −0.6), or plasma lactate, glucose, pH, hemoglobin, and electrolytes between both sampling sites at rest or at the 2 exercise levels. Conclusion:Arterialized fingertip blood samples at rest and during exercise can predict arterial carbon dioxide pressure, and can predict arterial plasma lactale, glucose, pH, hemoglobin, and electrolytes; but not arterial oxyhemoglobin saturation or arterial oxygen pressure.

Adding strength training, exercise intensity, and caloric expenditure to exercise guidelines in pregnancy.

Several versions of exercise guidelines for pregnancy have been published, the latest 9 years ago. These guidelines recommend 30 minutes or more of moderate exercise on most if not all days of the week for pregnant women in the absence of medical or obstetric complications. However, moderate-intensity exercise was not defined. In addition, the specific weekly energy expenditure of physical activity was not suggested. Recent research has determined that, compared with less vigorous activities, exercise intensity that reaches at least 60% of the heart rate reserve during pregnancy while gradually increasing physical-activity energy expenditure reduces the risk of gestational diabetes. To achieve the minimum expenditure of 16 metabolic equivalent task-h/wk, one could walk at 2 miles/h for 6.4 h/wk (2.5 metabolic equivalent task-hours, light intensity) or, preferably, exercise on a stationary bicycle for 2.7 h/wk (6 to 7 metabolic equivalent task-hours, vigorous intensity). To achieve the target expenditure of 28 metabolic equivalent task-hours per week, one could walk at 2.0 miles/h for 11.2 h/wk (2.5 metabolic equivalent task-hours, light intensity) or, preferably, exercise on a stationary bicycle for 4.7 h/wk (6 to 7 metabolic equivalent task-hours, vigorous intensity). The more vigorous the exercise, the less total exercise time is required. Light muscle strengthening performed during the second and third trimesters of pregnancy has minimal effect on newborn body size and overall health. On the basis of this and other information, updated recommendations for exercise in pregnancy are suggested.

Short-term variability of nitric oxide diffusing capacity and its components

When monitoring nitric oxide diffusing capacity (DL(NO)) in patients, it is necessary to distinguish natural biological variation from a real change in alveolar-membrane conductance. The short-term variability of single-breath DL(NO) has not been established. The aim was to determine the short-term variability DL(NO) in healthy subjects. Twelve healthy subjects performed single-breath hold diffusing capacity tests at rest over a 2-month period (eight separate sessions with 8+/-3 days between each session). Each subject inhaled 41+/-4 ppm NO and a standard diffusion mixture. DL(NO), which is a multiple of the membrane diffusing capacity for carbon monoxide (Dm(CO)), as well as carbon monoxide diffusing capacity (DL(CO)) and pulmonary capillary blood volume (V(c)) remained unaltered over the 2-month period (P>0.05). Reproducibility (calculated as 2.77 multiplied by the within-subject standard deviation) over eight sessions was 20, 5 and 8 mL min(-1)mmHg(-1) for DL(NO), DL(CO) and Dm(CO), respectively, and 19 mL for V(c) (when Dm(CO)=DL(NO)/2.42). DL(NO), DL(CO), Dm(CO) and V(c) remain unchanged over a period of 2 months. Since the inter-session variability is 20, 5 and 8 mL min(-1)mmHg(-1) for DL(NO), DL(CO) and Dm(CO), and 19 mL for V(c), a meaningful change should equal or exceed those values. While there is a small chance that week-to-week variation can also be partly due to mild pathophysiological changes, any differences that are below the reproducibility values are likely to be natural biological variation or technical variation of the equipment, rather than true physiological change.