摘要:

ABSTRACT.Concurrent with the study of performance and aerobic power of 12 highly trained, superior middle‐distance runners before, during and after 3 weeks of strenuous training at 2,300‐m altitude, observations were made pre‐ and post‐altitude on blood volume, BV, plasma volume, PV, cell volume, CV, hematocrit, Hctv, and the concentration and amount of hemoglobin, Hb. For comparative purposes, the same components were measured in 21 non‐athletic young men at or near sea level. Similar data on 27 black and white sharecroppers also were available for comparison. Since CV did not change at altitude, Hctvvalues obtained on eight occasions at altitude were used to calculate PV at altitude. The mean Hctvincreased 3.7% at altitude, which corresponds to a decrease or 6.6% in PV. The mean decrease in body weight, BW, was 2.1. In the runners BV in relation to BW was 21% greater than in 48 non‐athletes. Approximately one‐third of this larger BV is accounted for by the lower body fat of the runners. Cell volume, PV and total Hb, all in relation to BW, were greater in the runners than in the non‐athletes by 18, 24 and 16%, respectively. Consistent with the difference in PV and in CV, Hb concentration was 4% lower in the runners. It is concluded that endurance athletes have thin blood but so much of it that their total Hb exceeds that of non‐athletes. Aerobic power was dependent in part on Hb/kg not only in the runners but also in girl swimmers.

ISSN:0025-7990    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

ABSTRACT.Seven untrained and unacclimatized female subjects rested, walked for 40 minutes on a treadmill grade at 50% max&OV0312;o2, and recovered from exercise under two environmental conditions. The two conditions represented thermal neutrality (TA= 25°C) and a hot‐dry (TA= 48°C) condition. Thermoregulatory and metabolic measures were assessed. Significantly higher levels of &OV0312;o2, &OV0312;e, and heart rate occurred during exercise and recovery in 48°C compared to 25°C. Ventilation equivalent and oxygen pulse values suggested reduced metabolic efficiency in the heat. Resting Treinitially decreased in the heat returning to control values within 40 minutes. Comparable changes were not evident during rest in 25°C. The change in Treoccurring with exercise in the heat was double that in the 25°C condition. Body heat content rose 9 kcal/m2during the exercise period in the 25°C environment but was elevated 45 kcal/m2during the walk in the heat. The heat load of the 48°C environment altered thermal balance such that changes in circulatory and respiratory response mechanisms resulted in increased metabolic requirements.

ISSN:0025-7990    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

ABSTRACT.The study measured the effectiveness of a predetermined training intensity to induce cardiovascular improvements in sedentary college women. It was an attempt to clarify the question, “When does an exercise become training?” or “What work intensity is necessary for cardiovascular changes?”—quantitatively, an unresolved issue pertaining to the dosage of exercise. Twelve subjects, aged 17 to 21 years, participated in a treadmill training program fifteen minutes daily for four weeks. Six subjects (Group 1), trained at a heart rate of 125 beats per min and six subjects (Group 2), trained at a heart rate of 145 beats per min. Treadmill speeds were regulated during each training session so that the work intensity remained at the predetermined heart rate level. The test battery included basal HR and “all out” treadmill test variables (time at HR 180, max oxygen intake, max HR, and test run time) at pre‐ and post‐training; mid‐ and post‐training re‐runs at the second training day treadmill speeds; and treadmill speeds throughout the training. Thettest in various forms was used to treat the pre‐, pre‐ to ‐post, and post‐training data. Group 1 showed significant increases in the time required to elicit a heart rate of 180 beats per min and maximal oxygen intake, while Group 2 significantly increased total run time and maximal oxygen intake. It was concluded that a work intensity eliciting a heart rate of 125 beats per min provided sufficient but not minimal stimulus for training effects in sedentary young females.

ISSN:0025-7990    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

ABSTRACT.Forty‐four college women trained on a bicycle ergometer 2 times weekly for 10 weeks. Each session consisted of one continual “all‐out” ride at a cadence of 60 rpm, beginning at a work load of 360 kgm/min. The load was increased by 180 kgm/min every 2 min until the subject could not continue. Changes which occurred after training included higher maximal values for pulmonary ventilation, oxygen uptake, oxygen pulse, heart rate, and total work output, and a lower maximal ventilation equivalent. Immediately after the termination of training the subjects were assigned at random to 2 experimental groups which were then randomly assigned to 5‐or 10‐week detraining periods. The detraining periods produced increases in resting heart rate and maximal ventilation equivalent and decreases in total work and maximal values for pulmonary ventilation, oxygen uptake, and oxygen pulse. Losses in maximal values for oxygen uptake, oxygen pulse, and ventilation equivalent were greater for 10 than for 5 weeks of detraining. Improvements which occurred in maximal values for heart rate, pulmonary ventilation, and total work following training were retained to some degree after 10 weeks of detraining.

ISSN:0025-7990    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

ABSTRACT.These experiments were conducted to evaluate the effects of breathing O2‐enriched gas mixtures during exercise. Measurements of &OV0312;o2and &OV0312;co2were made with human subjects walking or running on a treadmill and with anin situmuscle preparation stimulated to perform maximal isometric contractions at various twitch rates. During maximal exercise in man, &OV0312;o2was 20% higher when breathing 80% O2than when breathing air. This was accompanied by a 30‐35% decrease in &OV0312;e and a slight decrease in &OV0312;co2. In submaximal work &OV0312;o2was still elevated when breathing O2‐enriched mixtures, in this case 30%. Neither &OV0312;e nor &OV0312;co2changed significantly. In thein situmuscle preparation, neither &OV0312;o2or &OV0312;co2changed during contractions, whether the animal breathed air or O2. Since increased metabolic rates in man should be accompanied by an increased &OV0312;co2, it is possible that the apparent increase in &OV0312;o2might be due to something other than an increased mitochondrial O2utilization.

ISSN:0025-7990    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

ABSTRACT.The increases above control of oxygen uptake (&Dgr;&OV0312;o2) and temperature (&Dgr;Tm) of the dog gastrocnemius‐plantaris muscle preparationin situwere determined during the last minute of 5 minutes of twitch contractions at 0.5,1,2,3,5 or 10/sec or of tetanic contractions (40/sec, 200 msec) at 12,20,40 or 60/min. The &Dgr;Tmincreased from .29 ± .07 to 1.54 ± .28 C° (mean ± standard error) with increasing twitch frequencies and from .70 ± .17 to 1.60 ± .22 C° with tetanic contractions. The &Dgr;&OV0312;o2increased to a peak of 139.7 ± 14.4 &mgr;l/g min at 5/sec during twitches but increased from 35.9 ± 4.1 to 104.0 ± 8.3 &mgr;l/g min with increasing tetanic frequencies. The &Dgr;Tmcaloric equivalent accounted for 23 to 40% of the &Dgr;&OV0312;o2caloric equivalent during twitches and for 51 to 63% with tetanic contractions. Differences in blood flow partially explain the different percentage ranges calculated. These low percentages limit the usefulness of &Dgr;Tmas an indicator of &Dgr;&OV0312;o2but since &Dgr;Tmincreases with contraction rate it can be used to indicate relative metabolic rates.

ISSN:0025-7990    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

ABSTRACT.The present study determined the relationship between maximum leg force (MLF) and various measures of leg composition to max&OV0312;o2measured on a treadmill (TM) and bicycle ergometer (BE). MLF was measured for N = 50 during pedaling at 60 rpm in the exact cycling pattern of a BE max&OV0312;o2test by coupling an isokinetic dynamometer directly with a Monark (Sweden) BE. Significant correlations (P < .01) were found between MLF vs max&OV0312;o2on the TM (r = .46) and BE (r = .40), body weight (r = .59), leg weight (r = .45), leg volume (r = .47) and lean body weight (r = .62). Although a low but significant r = .33 (P < .05) was obtained between MLF and TM and BE max&OV0312;o2differences, this correlation was not in the expected direction of a negative relationship (i.e., subjects able to exert more force with the legs have a smaller difference between TM and BE max&OV0312;o2). This correlation was reduced to r = .03 when heterogeneity in body size was statistically controlled by use of partial correlations. These partial correlations indicate that MLF and MLF relative to body weight, leg weight, leg volume, body composition and absolute max&OV0312;o2values accounts for less than two percent of the variability in TM and BE max&OV0312;o2, or the difference between TM and BE max&OV0312;o2, when these differences are expressed in either absolute (l/min) or percentage terms. Apparently, factors other than MLF or leg composition are associated with the 12.4% higher values of max&OV0312;o2on the TM (3.93 l/min; 54.8 ml/kg · min) compared with the BE (3.44 l/min; 48.1 ml/kg · min).

ISSN:0025-7990    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

ABSTRACT.Three male endurance athletes, 72‐74 years of age and holders of age‐group world track records, were selected for a detailed study of their body composition and physiological responses at rest and during exercise. In an attempt to better understand the process of aging and training in an aged population, comparisons were made with data from the normal population of similar age and with data from younger endurance athletes.The relative fat of these three athletes was well below the normal value for their age and approximate values seen in young endurance athletes. Their values for VC, FEV1.0, RV and TLC were within the normal range for their age, but well below those values reported for young endurance athletes. &OV0312;o2max and &OV0312;e were ˜ 50% and 60% respectively of the values obtained in young endurance athletes but ˜ 30‐40% greater than that seen in the normal, age‐matched population. The significance of these findings is discussed.

ISSN:0025-7990    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

ABSTRACT.The mortality of 396 Finnish champion skiers born from 1845 to 1910 was followed up to the end of 1967. Their median life expectation was 73.0 years. During the study the median life expectation of the general male population increased, but in 1956‐60 it still was 2.8 years shorter than that of the skiers. When the skiers were divided into those born before 1883 and those born during or after 1883, no trend was seen in their median life expectation. According to a parallel cross‐sectional study of surviving runners and skiers, former endurance athletes have low blood pressure, seldom smoke and are physically active. All these characteristics may contribute to their longevity.

ISSN:0025-7990    

出版商:OVID    

年代:1974

数据来源: OVID

摘要:

ABSTRACT.An objective method for predicting the minimum effective weight of high school wrestlers for certified weight purposes—the Tcheng‐Tipton Method—was field tested in Minnesota. Data were obtained from finalists at two State Tourneys. Data were also obtained on wrestlers within a nine‐school Conference at the beginning, middle, and end of a season. The formula is validated on the assumption that State Finalists represent wrestlers who are at their lowest effective weight (i.e., can sustain their skill against equals in repetitive matches). Data collection for the Method was accompanied by measurements of five skinfold sites to examine the implications of body composition variation in assessing individuals whose predicted weight is contested. The findings were reasonably consistent with the underlying assumption of validity, although the reliability of the Method was shown to warrant strengthening via more specific directions for measurement technique. Coach cooperation was encouraging, and the Method appears potentially efficacious.

ISSN:0025-7990    

出版商:OVID    

年代:1974

数据来源: OVID