Search PubMed⌕ Search

Biomedical subjects

K B Pandolf

Publications and source records attributed to K B Pandolf.

At least 127 records · Page 7Linked to original sources
PubMed1980

Exercise intensity: subjective regulation by perceived exertion.

The primary purpose of this investigation was to determine if a safe and effective physical conditioning heart rate (HR) could prescribed by perception of exertion. Ratings of perceived exertion (RPE) were requested from 10 normal adult men during treadmill exercise trials at 4.7, 6.5, 9.7, 11.3, and 12.9km/hr (T1). Subjects were then requested to subjectively regulate their own treadmill speed during 2 separate trials (T2 and T3) at the RPE reported for each speed during T1. Speed and HR at equivalent RPE were compared during T1, T2, and T3. Regression analyses revealed that there was no difference in speed across all RPE between the 3 trials; however, HR was seen to become progressively higher during T2 and T3 than during T1 as speed and RPE decreased. HR reliability was significant (p < 0.05) during running but not significant (p > 0.05) during walking. It is concluded that prescription of exercise by RPE can produce safe, effective, and reliable conditioning HR above 150bpm (80% HRmax) and running speeds above 9km/hr. Use of RPE for exercise prescription below these levels can result in inaccurate and unreliable conditioning heart rates. This method of exercise prescription has limitations and could result in dangerously high HR is used in cardiac rehabilitation programs, in which strict adherence to target HR is essential.

Adult↗
PubMed1980

Physiological responses of men and women to prolonged dry heat exposure.

Heat-acclimated men (n = 10) and women (n = 9) were exposed to hot-dry conditions (49 degrees C, 20% rh) for 4h to determine the effect of prolonged work in the heat on physiological differences between the sexes. Hourly exposures consisted of 10 min resting and 50 min walking at 1.34 m . s-1 (time-weighted metabolic rate = 175 and 151 W . m-2 for men and women, respectively). No significant difference in rectal temperature (Tre) was found between the sexes for each hour (h) of exposure. Heart rate (HR) of women, however, averaged 10-17 beats . min-1 higher than men. Mean skin temperature (Tsk) was also significantly higher in women throughout the exposure. For both sexes, the 4th-h Tre, HR, and Tsk were significantly higher than the preceding 3h. No sex related differences in total sweat rate (msw) or sweat sensitivity, as indicated by msw/delta Tre, were evident. It was concluded that: a) prolonged exposure to dry heat does not accentuate physiological differences between the sexes; b) women sweat at rates comparable to men over a 4-h period; c) 2-h acclimation sessions do not necessarily acclimate individuals for work of longer duration.

Acclimatization↗
PubMed1979

Effects of physical training and cardiorespiratory physical fitness on exercise-heat tolerance: recent observations.

Most authors agree that physical training in a cool environment improves tolerance to exercise in the heat and the rate of heat acclimatization, but the extent or degree of improvement remains controversial. The best improvement in heat tolerance for men is associated with intensive interval or continuous training at a training intensity greater than 50% of maximal oxygen uptake (Vo2max) for 8-12 weeks; the Vo2max should be increased 15-20%. Far less is known about the appropriate type, intensity and duration of endurance training associated with improved exercise-heat tolerance in women. The major benefits of physical training appear to apply to both short term (less than 2 hrs) or long term (greater than 2 hrs) exercise-heat exposures for men. Generally, individuals with high Vo2max values (previously trained and endurance athletes) are at an advantage in the heat. Utilization of proper physical training appears to produce about 50% of the total adjustment resulting from heat acclimatization, while increased fitness is associated with greater retention of acclimatization in cool environments. Female athletes appear somewhat better able to tolerate exercise in hot environments than nonathletic females while differences between highly trained females and males do not appear as dramatic as once thought.

Acclimatization↗
PubMed1978

Induced hyperthermia in sedated humans and the concept of critical thermal maximum.

The concept of critical thermal maximum (CTM) has been defined in the literature as the minimal high deep-body temperature that is lethal to an animal. In man the CTM has been estimated at 41.6--42.0 degrees C. Data are presented for sedated, unacclimatized, well-hydrated men heated 1 h at esophageal temperatures of 41.6--42.0 degrees C, without sequelae, except for modest elevation of serum enzymes in two of five patients. These data when combined with other observations in the literature suggest that CTM be redefined as the particular combination of exposure time at elevated body temperatures that results in either subclinical (CTM)s) or clinical (CTMc) injuries. Also presented is a mathematical technique, equivalent time at 42 degrees C (Teq 42 degrees), for expressing hyperthermia in terms of body temperature and exposure time.

Adolescent↗
PubMed1978

Influence of local and central factors in dominating rated perceived exertion during physical work.

The literature suggests two major factors determine rated perceived exertion during physical work. These two factors are a local factor, i.e., sensations or feelings of strain in the working muscles and/or joints; and a central factor, i.e., sensations or feelings primarily associated with the cardiorespiratory systems. In some experiments heart rate and minute ventilation (central vactors) appear to be the dominant cues for rated perceived exertion, while in others, local factors such as blood lactate concentration and muscular discomfort seem to be the prominent cues. However, it appears that when a particular cue is accentuated by either elevated rate, concentration or value over others it can dominate the over-all rating of perceived exertion. After evaluating the existing literature, a model has been introduced to evaluate differentiated ratings of perceived exertion (local and central) in comparison to the over-all measure. This model may help aid in a better understanding of the mechanisms by which the subjective perception of exertion is determined during different types of physical work.

Catecholamines↗
PubMed1977

Perceived exertion associated with breathing hyperoxic mixtures during submaximal work.

The effect of an enriched inspired oxygen concentration on perceived exertion (RPE) was investigated while running at two submaximal treadmill loads. Twelve males (VO2 max = 49.3 ml/kg-min) worked at 50% and 80% VO2 max, breathing either air or 80% O2-20% N2 in random order using a single blind technique. Subjects were evaluated while running for 10 min and during a 20 min recovery. Heart rate (HR), ventilation (VE), respiration rate (RR), tidal volume (VT) and RPE were measured before, during and after work. Blood lactate was measured 1 min after work. Oxygen concentration did not statistically affect HR, VE, RR or VT during exercise or recovery. At both loads, RPE at the end of exercise was significantly reduced breathing the hyperoxic mixture. At 50% VO2 max, mean RPE decreased from 11.2 breathing room air to 9.6 breathing 80% O2 and, 80% VO2 max, from 13.8 to 11.7 (P less than 0.01). Blood lactates were significantly reduced breathing 80% O2; from 23.4 mg to 13.3 at 50% VO2 max and from 55.5 to 36.5 at 80% VO2 max (P less than 0.01). The RPE correlated with lactate (r=0.64) at the end of work. Results indicate that during moderate and heavy work RPE is significantly affected by the inspired O2 concentration and there is a significant relationship between RPE and blood lactate.

Adult↗
PubMed1975

Differentiated ratings of perceived exertion during physical conditioning of older individuals using leg-weight loading.

Use of leg weights for physical conditioning was evaluated in 8 middle-aged male Ss; four Ss of similar age served as a control group. Pre- and post-training evaluation consisted of heart rate and oxygen uptake responses to five submaximal work loads which involved either level walking or cycling. Differentiated ratings of perceived exertion elicited for each work load were: a local muscular rating; a central or cardio-pulmonary rating; and an over-all or general rating. Submaximal heart rate decreased 6 to 9 beats/min. from pretraining values for all work load after training. The differentiated ratings for training generally reflected a reduced strain on the cardiovascular system and also improved functioning of the working muscles with training. However, when one set of sensations dominated the exertional perception the others appear to have been perceptually de-emphasized. Local muscular factors seemed to dominate the exertional perception for cycling, but central factors appeared to play a more important role for treadmill walking, at least within the range of velocities investigated.

Adult↗
PubMed1975

Physical conditioning of less fit adults by use of leg weight loading.

Physical conditioning using weighted ankle spats was evaluated in eight men in the age range 33 to 45 years (mean, 38.4). Evaluation consisted of pretraining and posttraining heart rate (HR) and oxygen uptake (VO2) responses to five submaximal work loads: cycling six minutes at 600 kilopond meter per minute (kpm/min); level walking for ten minutes at both 4.0 and 5.6 km/hr with and without a 1.5-kg weight spat added to each ankle. After the initial baseline evaluation, subjects wore 1.5-kg weight spats on both ankles for three weeks and were reevaluated; during the next three-week period weight was increased to 2.25 kg per ankle. Following the six-week evaluation period, subjects did not wear ankle spats, and detraining was evaluated after three weeks. A control group of four subjects was evaluated at these same submaximal work loads on three different occasions with three-week periods between evaluations. The experimental group wore the spats about 13.5 hours per day and averaged 6.85 km/day (4.25 miles per day) during training. After six weeks of training, submaximal HR decreased 6 to 9 beats per minute (P smaller than 0.05) from pretraining values for all five submaximal work loads; predicted VO2 max and predicted work capacity to achieve a HR of 170 beats per minute increased by approximately 10%. Detraining submaximal HR responses increased slightly, but not significantly, from post six-week training responses. Control group submaximal responses were unchanged between evaluations. It was concluded that individuals who initially possess a low level of cardiorespiratory fitness may have a low threshold for training. Thus, leg weight conditioning may be extremely useful for rehabilitation of patients and for sedentary middle-aged men as special adaptation prio to more high intensity training.

Adaptation, Physiological↗