Backward extrapolation of VO2max values from the O2 recovery curve.

The purpose of this study was to validate a method for measuring Vo2max in field conditions. In order to do so, Vo2max obtained by backward extrapolation of the O2 recovery curve at time zero of recovery (BE), was compared to the Vo2max measured directly at the end of a continuous multistage test (Exercise). The optimal way to determine Vo2max was by using a single component exponential least-squares regression on the first three or four 20 x recovery values. When a three-way valve was used to collect expired air immediately at the start of recovery (n=20), BE Vo2max (X- +/- SD=56.5 +/- 7.4 ML KG-1 MIN-1) WAS NOT SIGNIFICANTLY DIFFERENT FROM Exercise Vo2max (56.1 +/- 7.6). When subjects (n=16) connected themselves to another breathing valve immediately at the end of the test to simulate field conditions BE and Exercise Vo2max were similar (63.9 +/- 6.7 and 63.1 +/- 7.0, respectively) as long as a 3 s correction was made for the delay caused by this procedure. BE and Exercise Vo2max were 59.8 +/- 8 and 59.2 +/- 8.1 for the 36 subjects; the Pearson's correlation coefficient was 0.92. BE Vo2max measured on 11 additional runners tested on a track (62.6 +/- 13) yielded similar results as Exercise Vo2max measured on the treadmill using the same protocol (61.2 +/- 13.3). The backward extrapolation method appears to be valid to measure Vo2max when the air collecting equipment might otherwise be cumubersome during actual sport and/or laboratory conditions.

An on-ice aerobic maximal multistage shuttle skate test for elite adolescent hockey players.

The aim of this study was to design an on-ice test to predict V.O (2max) in ice hockey players. 30 elite hockey players (age 14.7 +/- 1.5 years) participated in this study. The oxygen uptake was assessed at submaximal and maximal velocities during an on-ice intermittent maximal multistage shuttle skate test with a 1-min/0.5-min work/rest ratio. The procedure consisted of skating back and forth on a distance of 45 m (stop and go) while following a pace fixed by an audible signal: initial velocity of 3.5 m . s (-1) with increments of 0.2 m . s (-1) every stage. The skating multistage aerobic test (SMAT) enabled the prediction of the V.O (2max) (ml . kg (-1) . min (-1)) from the maximal velocity (m . s (-1)) by means of the following regression equation: V.O (2max) = 18.07 x (maximal velocity) - 35.596 (r = 0.97, SEE = 3.01). The test-retest correlation was 0.92 and SEE = 0.56 stage (n = 23). Following the SMAT validation, an additional group of 112 elite male (age = 14.2 +/- 1.3 years) and 31 elite female (age = 14.0 +/- 1.2 years) ice hockey players performed both the 20-m shuttle run test and the SMAT, which was more specific and accurate to predict V.O (2max). The overall results suggest that the SMAT is highly specific, valid and reliable for the prediction of V.O (2max) of ice hockey players.

Spurious and actual improvement in the treatment of preoccupying thoughts by thought-stopping.

Two clients troubled by preoccupying thoughts were treated by a version of thought-stopping described by Wolpe (1969) which has been infrequently reported so far. The frequency of spontaneous intrusive thoughts as they occurred within sessions was found to be a useful measure of clinical outcome, but it is suggested that careful control and definition of variations in procedure is necessary in order to eliminate spurious results. Treatment was found to produce an improvement which was maintained at follow-up.

Energetics of indoor track cycling in trained competitors.

Steady-state track VO2 was estimated by means of the retroextrapolation method in seventeen competitive male cyclists at speeds ranging from 28 to 43 km.h-1. Peak VO2 was also determined using an ergocycle multistage test (80 rev.min-1). Results showed large VO2 variations at similar speeds on the track (SEE greater than 10% Y; n = 17). Third degree regressions were the most accurate to describe the evolution of VO2 with speed, while the units ml.kg-0.667.min-1 showed better correlations and lower dispersions than 1.min-1, ml.kg-1.min-1, and 1.min-1.m-2. When categorized according to the Québec Cycling Federation ranking, (elites: n = 6; nonelites: n = 11), the elites tended to demonstrate to a lower mean VO2 for the range of velocities studied. The difference was, however, not statistically significant (P greater than 0.05). Interindividual variations were reduced by expressing VO2 and speed as relative percentages of maximal values in ten subjects: % MAP = 6.475 e exp [0.0274% MAS] where % MAP = track VO2/laboratory peak VO2, and % MAS = speed/speed associated with peak VO2 on the track. No significant difference was observed between track and ergocycle peak VO2 (P greater than 0.05), indicating the validity of the 80 rev.min-1 protocol for laboratory evaluation of racing cyclists. The concept of cycling economy as a contributing factor to performance and applications of the % MAP-% MAS relationship are discussed.

Comparison of mathematically determined blood lactate and heart rate "threshold" points and relationship with performance.

The purpose of this study was to investigate the relationship between threshold points for heart rate (Thfc) and blood lactate (Thla) as determined by two objective mathematical models. The models used were the mono-segmental exponential (EXP) model of Hughson et al. and the log-log (LOG) model of Beaver et al. Inter-correlations of these threshold points and correlations with performance were also studied. Seventeen elite runners (mean, SD = 27.5, 6.5 years; 1.73, 0.05 m; 63.8, 7.3 kg; and maximum oxygen consumption of 67.8, 3.7 ml.kg-1.min-1) performed two maximal multistage running field tests on a 183.9-m indoor track with inclined turns. The initial speed of 9 km.h-1 (2.5 m.s-1) was increased by 0.5 km.h-1 (0.14 m.s-1) every lap for the fc test and by 1 km.h-1 (0.28 m.s-1) every 4 min for the la test. After fitting the la or the fc data to the two mathematical models, the threshold speed was assessed in the LOG model from the intersection of the two linear segments (LOG-la; LOG-fc) and in the EXP model from a tangent point (TI-la; TI-fc). Thla and Thfc speeds computed with the two models were significantly different (P less than 0.001) and poorly correlated (LOG-la vs LOG-fc: r = 0.36, TI-la vs TI-fc: r = 0.13). In general, Thfc were less well correlated with performance than Thla. With two different objective mathematical models, this study has shown significant differences and poor correlations between Thla and Thfc.(ABSTRACT TRUNCATED AT 250 WORDS)

A maximal multistage 20-m shuttle run test to predict VO2 max.

In order to validate a maximal multistage 20-m shuttle run test for the prediction of VO2 max, 91 adults (32 females and 59 males, aged 27.3 +/- 9.2 and 24.8 +/- 5.5 year respectively and with mean VO2 max (+/- SD) of 39.3 +/- 8.3 and 51.6 +/- 7.8 ml . kg-1 . min-1 respectively) performed the test and had VO2 max estimated by the retroextrapolation method (extrapolation to time zero of recovery of the exponential least squares regression of the first four 20-s recovery VO2 values). Starting at 8 km . h-1 and increasing by 0.5 km . h-1 every 2 min, the 20-m shuttle run test enabled prediction of the VO2 max (y, ml . kg-1 . min-1) from the maximal speed (x, km . h-1) by means of the following regression equation: y = 5.857x - 19.458; r = 0.84 and SEE = 5.4. Later, the multistage protocol was slightly modified to its final version, in which the test started at stage 7 Met and continued with a 1 Met (3.5 ml O2 . kg-1 . min-1) increment every 2 min. Twenty-five of the 91 subjects performed the 20-m shuttle test twice, once on a hard, low-friction surface (vinyl-asbestos tiles) and another time on a rubber floor, as well as a walking maximal multistage test on an inclined treadmill. There was no difference between the means of these tests or between the slopes of the VO2max - maximal speed regressions for the two types of surfaces. The 20-m shuttle run test and another maximal multistage field test involving continuous track running gave comparable results (r = 0.92, SEE = 2.6 ml O2 . kg-1 . min-1, n = 70). Finally, test and retest of the 20-m shuttle run test also yielded comparable results (r = 0.975, SEE = 2.0 ml O2 . kg-1 . min-1, n = 50). It is concluded that the 20-m shuttle run test is valid and reliable test for the prediction of the VO2 max of male and female adults, individually or in groups, on most gymnasium surfaces.

Speed reliability of cassette and tape players.

The playback speed of tape players directly affects the accuracy of some fitness tests. New and used portable cassette (n = 28) and tape (n = 16) players were generally found accurate (playback speed error less than 2% tolerance limit). The apparatus showed almost no speed variation over four consecutive trials. Four portable cassette players were also checked three times over ten days without any appreciable change in speed. Four cassette players (14%) were, however, found inaccurate making it necessary to possess a rapid method of checking speed accuracy. Similar or better results were found for open reel tape recorders.

VO2max of cyclists from treadmill, bicycle ergometer and velodrome tests.

The purpose of this study was to measure the VO2max of trained cyclists on the treadmill (means +/- SD = 54.7 +/- 6.3 ml kg-1 min-1), while riding a bicycle on a velodrome track at 100 rpm (53.7 +/- 7.8) and on the bicycle ergometer at 60 rpm (62.4 +/- 8.1): VO2max beeing the highest in the latter case (p less than 0.05). The highest maximal HR, 188 +/- 6 beats min-1, was observed during the treadmill test, while estimates of 184 +/- 6 and 179 +/- 7 were obtained for the velodrome and the bicycle ergometer tests, respectively. No significant differences were observed in the blood lactate concentrations (treadmill: 10.35 +/- 4.01 bicycle ergometer: 10.25 +/- 2.29 velodrome: 10.95 +/- 1.51 mmol L-1. In conclusion, bicycle ergometer tests might not be specific enough to evaluate the ability of trained cyclists to perform an endurance or aerobic task on the track. Trained cyclists, as opposed to untrained ones, appear to achieve higher VO2max on the bicycle ergometer as compared to the treadmill.

The multistage 20 metre shuttle run test for aerobic fitness.

A maximal multistage 20 m shuttle run test was designed to determine the maximal aerobic power of schoolchildren, healthy adults attending fitness class and athletes performing in sports with frequent stops and starts (e.g. basketball, fencing and so on). Subjects run back and forth on a 20 m course and must touch the 20 m line; at the same time a sound signal is emitted from a prerecorded tape. Frequency of the sound signals is increased 0.5 km h-1 each minute from a starting speed of 8.5 km h-1. When the subject can no longer follow the pace, the last stage number announced is used to predict maximal oxygen uptake (VO2max) (Y, ml kg-1 min-1) from the speed (X, km h-1) corresponding to that stage (speed = 8 + 0.5 stage no.) and age (A, year): Y = 31.025 + 3.238 X - 3.248A + 0.1536AX, r = 0.71 with 188 boys and girls aged 8-19 years. To obtain this regression, the test was performed individually. Right upon termination VO2 was measured with four 20 s samples and VO2max was estimated by retroextrapolating the O2 recovery curve at time zero of recovery. For adults, similar measurements indicated that the same equation could be used keeping age constant at 18 (r = 0.90, n = 77 men and women 18-50 years old). Test-retest reliability coefficients were 0.89 for children (139 boys and girls 6-16 years old) and 0.95 for adults (81 men and women, 20-45 years old).(ABSTRACT TRUNCATED AT 250 WORDS)

Failure to obtain a unique threshold on the blood lactate concentration curve during exercise.

The purpose of this study was to compare various methods and criteria used to identify the anaerobic threshold (AT), and to correlate the AT obtained with each other and with running performance. Furthermore, a number of additional points throughout the entire range of lactate concentrations [La-] were obtained and correlated with performance. A group of 19 runners [mean age 33.7 (SD 9.6) years, height 173 (SD 6.3) cm, body mass 68.3 (SD 5.4) kg, maximal O2 Uptake (VO2max) 55.2 (SD 5.9) ml x kg(-1) x min(-1)] performed a maximal multistage treadmill test (1 km x h[-1] every 3.5 min) with blood sampling at the end of each stage while running. All AT points selected (visual [La-], 4 mmol x l(-1) [La-], 1 mmol x l(-1) above baseline, log-log breakpoint, and 45 degrees tangent to the exponential regression) were highly correlated one with another and with performance (r > 0.90) even when there were many differences among the AT (P < 0.05). The additional points (ranging from 3 to 8 mmol x l(-1) [La-], 1 to 6 mmol x l(-1) [La-] above the baseline, and 30 to 70 degrees tangent to the exponential curve of [La-]) were also highly correlated with performance (r > 0.90). These results failed to demonstrate a distinct AT because many points of the curve provided similar information. Intercorrelations and correlations between AT and performance were, however, reduced when AT were expressed as the percentage of maximal treadmill speed obtained at AT or percentage of VO2max. This would indicate that different attributes of aerobic performance (i.e. maximal aerobic power, running economy and endurance) are measured when manipulating units. Thus, coaches should be aware of these results when they prescribe an intensity for training and concentrate more on the physiological consequences of a chosen [La-] rather than on a "threshold".

VO2 peak during free swimming using the backward extrapolation of the O2 recovery curve.

The purpose of this study was to evaluate the accuracy and feasibility of estimating oxygen consumption (VO2) during maximal swimming by using the backward extrapolation (BE) of the VO2 recovery curve to time zero. Two series of experiments were conducted. In the first, the validity of the BE method was ascertained by comparing the VO2 peak values obtained during free swimming (Douglas bag technique) with those estimated by the BE method during recovery after the same tests. These results were also compared with VO2 peak measured during uphill treadmill running. VO2 peak measured during maximal free swimming and estimated by the BE method during the recovery period of that test, were not significantly different. No significant difference was found between VO2 peak uphill treadmill running and free swimming. In the second series of experiments, VO2 peak was measured in each of 28 swimmers during uphill running (conventional method) and during unimpeded swimming using the BE method. The mean value was significantly higher during swimming (mean = 3.37) than during running (mean = 3.23). Seventy-five percent of the subjects had higher VO2 peak during swimming. The swimming speed during maximal swimming effort was 10% higher when the BE method was used then when the same subjects were tested by the conventional Douglas bag technique. The BE method is reliable and valid way to measure VO2 peak in maximal swimming and allows the swimmer to use his specifically trained musculature fully.