Pattern of developing the performance template.

BACKGROUND: The pattern of energy expenditure during sustained high-intensity exercise is influenced by several variables. Data from athletic populations suggest that a pre-exercise conceptual model, or template, is a central variable relative to controlling energy expenditure. AIMS: The aim of this study was to make systematic observations regarding how the performance template develops in fit individuals who have limited specific experience with sustained high-intensity exercise (eg, time trials). METHODS: The study was conducted in four parts and involved measuring performance (time and power output) during: (A) six 3 km cycle time trials, (B) three 2 km rowing time trials, (C) four 2 km rowing time trials with a training period between trials 2 and 3, and (D) three 10 km cycle time trials. All time trials were self-paced with feedback to the subjects regarding previous performances and momentary pace. RESULTS: In all four series of time trials there was a progressive pattern of improved performance averaging 6% over the first three trials and 10% over six trials. In all studies improvement was associated with increased power output during the early and middle portions of the time trial and a progressively greater terminal rating of perceived exertion. Despite the change in the pattern of energy expenditure, the subjects did not achieve the pattern usually displayed by athletes during comparable events. CONCLUSIONS: This study concludes that the pattern of learning the performance template is primarily related to increased confidence that the trial can be completed without unreasonable levels of exertion or injury, but that the process takes more than six trials to be complete.

Effect of competitive distance on energy expenditure during simulated competition.

Concepts of how athletes should expend their aerobic and anaerobic energetic reserves are generally based on results of tests where an "all out" strategy is imposed on/required from the athlete. We sought to determine how athletes spontaneously expend their energetic reserves when the only instruction was to finish the event in minimal time, as in competition. Well trained, and task habituated, road cyclists (N = 14) completed randomly ordered laboratory time trials of 500 m, 1000 m, 1500 m and 3000 m on a windload braked cycle ergometer. The pattern of aerobic and anaerobic energy use was calculated from total work accomplished and V.O (2) during the trials. The events were completed in 40.3 +/- 0.6 s, 87.4 +/- 4.1 s, 133.8 +/- 6.6 s and 296.0 +/- 7.2 s. The peak V.O (2) during the terminal 200 m of all events was similar (2.72 +/- 0.22, 3.01 +/- 0.34, 3.23 +/- 0.44 and 3.12 +/- 0.13 l x min (-1)). In all events, the initial power output and anaerobic energy use was high, and decreased to a more or less constant value over the remainder of the event. However, the subjects seemed to reserve some ability to expend energy anaerobically for a terminal acceleration which is contrary to predictions of an "all out" starting strategy. Although the total work accomplished increased with distance (23.14 +/- 4.24, 34.14 +/- 6.37, 43.54 +/- 6.12 and 78.22 +/- 8.28 kJ), the energy attributable to anaerobic sources was not significantly different between the rides (17.29 +/- 3.82, 18.68 +/- 8.51, 20.60 +/- 6.99 and 23.28 +/- 9.04 kJ). The results are consistent with the concept that athletes monitor their energetic resources and regulate their energetic output over time in a manner designed to optimize performance.

Physical activity and exercise training prescriptions for patients.

The dominant outcome from exercise prescription is an increase in various markers of exercise capacity. A very large group of studies have demonstrated that the VO2max is increased in response to exercise performed according to well-accepted principles of exercise prescription. Other markers of exercise capacity, such as the VT, also improve substantially following exercise training. Finally, improvement in exercise capacity is generally related to improved quality of life, particularly in patients with exercise capacity limited by various disease processes. Beyond the specific physiologic gains from training, exercise contributes to a better overall clinical outcome. Although there are few data conclusively demonstrating that exercise independently causes favorable changes in other risk factors, it should be recognized that exercise can contribute indirectly to modulation of other risk factors. Exercise represents positive health advice. Since most of our other recommendations to patients are in the nature of negative advice (e.g., don't smoke, don't eat high-fat foods), and since people are infamous for ignoring negative advice, the value of using a positive recommendation that may indirectly lead the patient to discontinue bad behaviors can hardly be overstated.

Comparison of incremental treadmill exercise and free range running.

PURPOSE: The aim of this study was to compare physiological responses during incremental treadmill exercise and free range running. METHODS: Fifteen competitive cross-country runners performed an incremental treadmill test and an unpaced 1-mile run on an indoor 200-m track. Physiological variables (VO(2peak), HR(peak), VO(2) x HR(-1)(peak), V(Epeak)) were measured using a portable metabolic analyzer. Blood lactate was measured post exercise. Outcome variables were analyzed with repeated measures ANOVA. RESULTS: Although directionally similar to previous studies with cycle ergometry, the observed peak values (track vs treadmill) for VO(2) (63.0 +/- 7.4 vs 61.9 +/- 7.2 mL x kg(-1) x min(-1)), V(E) (147 +/- 37 vs 144 +/- 30 L x min(-1)), HR (188 +/- 5 vs 189 +/- 7 beats.min-1), and VO(2) x HR(-1) (22.1 +/- 4.4 vs 21.5 +/- 4.5) were not significantly different. The observed peak values for blood lactate (14.4 +/- 3.3 vs 11.7 +/- 3.0 mmol x L(-1)) were significantly (P < 0.05) different. CONCLUSIONS: The results are not in full agreement with previous findings from cycling studies with the exception of post exercise blood lactate. Whether this represents a fundamental lack of effect of free range exercise or is related to mode specificity remains to be determined.

Metabolic responses associated with deer hunting.

PURPOSE: Deer hunting is a popular recreational activity with a high rate of cardiovascular events. Previous studies have demonstrated large HR responses during deer hunting. This study compared the HR and metabolic costs of maximal treadmill (TM) exercise with those of hiking while deer hunting and while dragging a deer. METHODS: Healthy male volunteers (N = 16) performed a maximal TM exercise test, a 0.8-km hiking test, and a 0.4-km dragging test over lightly rolling terrain. VO2 was measured by portable spirometry and HR by radiotelemetry. RESULTS: HR averaged 74.0 +/- 7.0% and 89.1 +/- 4.5% of peak TM HR during the hike and drag, respectively. The peak HR observed during hiking and dragging was 83.2 +/- 6.0% and 94.9 +/- 4.2% of peak TM HR, respectively. VO2 averaged 62.2 +/- 15.8% and achieved a peak of 77.2 +/- 19.0% of TM VO2 while hiking. This corresponded to 86.8 +/- 17.3% and 108.1 +/- 22.3% of ventilatory threshold (VT), respectively. VO2 averaged 72.3 +/- 21.0% and achieved a peak of 91.2 +/- 21.4% of peak TM VO2 while dragging the deer. This corresponded to 101.5 +/- 27.7% and 128.5 +/- 26.8% of VT, respectively. The VO2/HR relationship showed significant (P < 0.05) difference between the dragging test and the TM test with a disproportionately high HR. The VO2/HR relationship between the hiking and TM tests was comparable. CONCLUSION: In part, the previously described large HR responses and high rate of cardiovascular complications associated with deer hunting may attributable to the elevated metabolic costs of associated activities.

Development of a maximal testing protocol for the NordicTrack cross-country ski simulator.

PURPOSE: The purpose of this study was to develop a valid VO2max testing protocol for the NordicTrack (NT) cross-country ski simulator. METHODS: To be considered a valid protocol, it was felt that the maximal values obtained from the cross-country skiing (XC) test should be similar to those obtained from a maximal graded treadmill (TM) test. During pilot testing, cadence (strides x min(-1), arm resistance, leg resistance, and grade were individually manipulated to study the effect on measured VO2. A protocol for the NT was developed from the findings of the pilot study, and the results were compared with a TM VO2max test utilizing the Bruce protocol. Thirteen male and 15 female volunteers (aged 22-49 yr) served as subjects and completed both tests in random order. The maximal physiological responses from the XC and TM max tests were compared using paired t-tests. RESULTS: There were no significant (P>0.05) differences in maximal VO2 (42.5 vs. 42.6 mL x kg(-1) x min(-1); 3.27 vs. 3.31 L x min(-1)), heart rates (HR; 185 vs. 185 bpm), or ratings of perceived exertion (RPE; 19.0 vs. 19.1) for the XC and TM tests. There were significant (P<0.05) differences for maximal VE (124.5 vs. 118.6 L x min(-1)) and respiratory exchange ratio (RER; 1.15 vs. 1.21) between the XC and TM tests, respectively. CONCLUSIONS: It was concluded that the testing protocol developed for the NT XC simulator is valid and can be expected to elicit similar maximal values when compared with TM testing.

Cranberry extract inhibits low density lipoprotein oxidation.

Cranberry juice consumption is often used for the treatment of urinary tract infections, but the effect of cranberry juice on heart disease has not been investigated. We evaluated how a cranberry extract containing 1,548 mg gallic acid equivalents/liter (initial pH=2.50) affected low density lipoprotein (LDL) oxidation induced by 10 micromolar cupric sulfate. When LDL oxidation took place in the presence of diluted cranberry extracts, the formation of thiobarbituric acid reactive substances (TBARS) and LDL electrophoretic mobility were reduced. LDL electrophoretic migration was also reduced when the cranberry extract had a pH of 7.00 prior to dilution. This study suggests that cranberry extracts have the ability to inhibit the oxidative modification of LDL particles.

The physiological responses to walking with and without Power Poles on treadmill exercise.

Power Poles are specially constructed, rubber-tipped ski poles designed for use during walking. Using Power Poles simulates the arm motion of cross-country skiing, thus increasing the muscle mass used during walking. This study investigated the potential increases in exercise intensity and energy cost associated with the use of walking poles. Thirty-two apparently healthy volunteers (16 men and 16 women) between the ages of 19 and 33 years participated. Each completed a treadmill maximal oxygen consumption (VO2max) test and two randomly assigned, submaximal walking trials (one with poles and one without poles) on separate days. Each walking trial was conducted on a level treadmill, for 20 minutes, at an identical self-selected pace. Expired gases, heart rate in beats per minute (bpm), and ratings of perceived exertion (RPE) were recorded each minute. Results between trials were compared using repeated measures analysis of variance and Tukey's post hoc tests. It was found that walking with poles resulted in an average of 23% (4.4 ml.kg-1.min-1) higher VO2, 22% higher caloric expenditure (1.5 kcal.min-1), and 16% (18 bpm) higher heart rate responses compared to walking without poles on a treadmill. RPE values averaged 1.5 units higher with the use of the poles, and the pattern of responses between conditions was similar for men and women. It is concluded that the use of Power Poles can increase the intensity of walking at a given speed and, thus, may provide additional training benefits to walkers.

Acute responses to using walking poles in patients with coronary artery disease.

PURPOSE: This study was designed to assess the safety and effectiveness of walking when using 1-lb walking poles in Phase III/IV cardiac rehabilitation patients. METHODS: Following instruction on the proper use of the poles and adequate time to practice, each subject completed two 8-minute walking trials on a level treadmill either with or without walking poles. Each trial was conducted at an identical speed for each subject in a randomized order. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and ratings of perceived exertion (RPE) were recorded every 2 minutes during each trial, while ECG responses (ST segment changes and dysrhythmias) were monitored continuously. RESULTS: Walking with poles significantly (P < .05) increased the energy cost of walking by 21% (3.8 mL/kg/min) compared to walking without poles. There were also significant (P < .05) increases in HR (14 bpm), SBP (16 mm Hg), and DBP (4 mm Hg) when comparing conditions. Calculated oxygen pulse (mL O2.heart beat) values indicated that changes in HR were consistent with the increase in VO2 and were not related to a pressor response mechanism. The only dysrhythmias noted were isolated PVCs, with no differences in the frequency of occurrence between trials. There were no adverse ST segment changes with either trial. CONCLUSIONS: These data demonstrate that at a given speed, the use of 1-lb walking poles can safely increase the intensity of walking exercise in Phase III/IV cardiac rehabilitation patients.

Internships in cardiopulmonary rehabilitation. Think win-win.

From a student's perspective, completing an internship program is the final, and maybe the most important step in his or her academic career. He or she finally gets a chance to put theory into practice and to see if he or she truly enjoys his or her chosen field. Through hard work and dedication, the efforts should provide her/himself with the practical skills and experiences necessary to propel her/himself into the work force. For the program, having interns can be viewed as just having an "extra hand," but with the proper commitment it can be much more rewarding. It is a unique opportunity to get a fresh new perspective on your own program, and a chance to mold students into eager young professionals. The internship experience truly is a "Win-Win" situation. Through the efforts of combined education--the internship site and the cardiopulmonary rehabilitation program working together--they can ensure that tomorrow's practitioners will be of the highest quality.

Physiological responses to in-line skating compared to treadmill running.

The physiologic responses to in-line skating were compared to those during treadmill running in 16 active males (18-37 yr). Each subject performed a VO2max test during in-line skating and treadmill running using speed-incremented, discontinuous protocols. Protocols were designed so that each subject completed 4-6 stages. Stages were 3 min in duration and separated by a 5-min rest period. It was found that absolute VO2max (4.19 vs 4.44 l.min-1, P = 0.045), relative VO2max (56.8 vs 59.9 ml.kg-1.min-1, P = 0.054), and HRmax (189 vs 194 b.min-1, P < 0.05) were lower for in-line skating compared to treadmill running. Regression analyses were used to determine the submaximal relationship between modalities. There were no significant (P > 0.05) differences in the slope and y-intercept of the HR/VO2 relationship, indicating a similar metabolic load at a given heart rate for both modes of exercise. Skating between 17.7-20.9 km.h-1 corresponded to 60-75% of VO2max or 75-90% of HRmax, which are common training intensities and within the guidelines recommended by the ACSM. Across the speeds investigated, caloric expenditure was 9.5-19.0 kcal.min-1. These results indicate that in-line skating elicits physiological responses comparable to treadmill running and thus would be another exercise alternative for improving aerobic capacity or maintaining body weight.

Walking for health and fitness.

Recent studies have linked regular physical activity with reduced likelihood of developing coronary heart disease. Even low- and moderate-intensity exercise such as walking, when carried out consistently, is associated with important cardiovascular health benefits. Walking has also been shown to reduce anxiety and tension and aid in weight loss. Regular walking may help improve cholesterol profile, help control hypertension, and slow the process of osteoporosis. Recent physiological studies have demonstrated that brisk walking provides strenuous enough exercise for cardiovascular training in most adults. A recently developed submaximal 1-mile walk test provides a simple and accurate means for estimating aerobic capacity and guiding exercise prescription. These new insights and tools will assist the clinician in the prescription of safe and effective walking programs.

Estimation of VO2max from a one-mile track walk, gender, age, and body weight.

The purpose of this investigation was to explore an alternative field test to estimate maximal oxygen consumption (VO2max) using a one-mile walk test. VO2max was determined in 343 healthy adult (males = 165, females = 178) subjects 30 to 69 yr using a treadmill protocol (mean +/- SD: VO2max = 37.0 +/- 10.7 ml X kg-1 X min-1). Each subject performed a minimum of two, one-mile track walks as fast as possible. The two fastest walks (T1, T2) with elapsed times within 30 s were used for subsequent analyses. Heart rates were monitored continuously and recorded every one-quarter mile. Multiple regression analysis (best sub-sets) to estimate VO2max (l X min-1) yielded the following predictor variables: track walk-1 time (T1); fourth quarter heart rate for track walk-1 (HR 1-4); age (yr); weight (lb); and sex (1 = male, 0 = female). The best equation (N = 174) was: VO2max = 6.9652 + (0.0091*WT) - (0.0257*AGE) + (0.5955*SEX) - (0.2240*T1) - (0.0115*HR1-4); r = 0.93, SEE = 0.325 l X min-1. Comparing observed and estimated VO2max values in a cross-validation group (N = 169) resulted in r = 0.92, SEE = 0.355 l X min-1. Generalized and sex-specific equations to estimate VO2max (ml X kg-1 X min-1) were also generated. The accuracy of estimation as expressed by SEE was similar among the equations. The results indicate that this one-mile walk test protocol provides a valid sub-maximum assessment for VO2max estimation.