Effects of 4-wk training using V_max/T_max on V̇O_2max and performance in athletes

Abstract

Effects of 4-wk training using V_max/T_max on V̇O_2max and performance in athletes. Med. Sci. Sports Exerc., Vol. 31, No. 6, pp. 892-896, 1999.

Purpose: 

The aim of this study was to determine the effects of a 4-wk individualized training program using V_max as the exercise intensity and utilizing between 60 and 75% of a subject's T_max as the exercise duration.

Methods: 

Five male, middle-distance, trained subjects with the following characteristics (mean ± SD): age, 22.8 ± 4.5 yr; height, 181 ± 4.7 cm; weight, 74.1 ± 3.2 kg; skinfolds based on five areas, 35.9 ± 3.9; and V̇O_2max, 61.5 ± 6.1 mL O₂·kg·min⁻¹ volunteered to participate in this study. Before the training program, the subjects completed a 3000-m time trial, and three each of V̇O_2max/V_max and T_max tests. Subjects then completed a 4-wk training program on the treadmill and were then retested on the V̇O_2max/V_max and T_max tests.

Results: 

Pretraining versus posttraining results showed significant (P < 0.05) increases in average V_max (20.5 km·h⁻¹ vs 21.3 km·h⁻¹ posttraining), T_max (225.5 s vs 300.9 s posttraining), and V̇O_2max (61.5 mL O₂·kg·min⁻¹ vs 64.5 mL O₂·kg·min⁻¹). The 3000-m time trial decreased significantly from a pretraining value of 616.6 s to a posttraining value of 599.6 s (P < 0.05).

Conclusions: 

The results of this study indicate that by utilizing between 60 and 75% of T_max as an exercise duration and using V_max as an exercise intensity that these two parameters can be extremely valuable in the prescription of exercise programs for athletes.

There are currently a number of methods proposed as viable means of obtaining physiological and performance related improvements, including the anaerobic threshold (AT), lactate threshold (LT), ventilatory threshold (VT), critical power (CP), critical running velocity, onset of blood lactate accumulation (OBLA), and V̇O_2max to name a few. Hill and Rowell ⁽¹²⁾, however, believe the physiological significance of many of these parameters or the rationale for using them to prescribe exercise training intensity has not been clearly elucidated.

A more recently investigated variable is the v V̇O_2max or V_max, which a number of authors ^{(3,4,6,8,10,11-13)} have defined as the speed at which an athlete is running when V̇O_2max is elicited. Billat et al. ⁽⁷⁾ have further defined V_max as the minimal running velocity that elicits V̇O_2max. The V_max has been shown to be an indicator of performance in middle- and long-distance running events ^(2,3,14,16). Morgan et al. ⁽¹⁴⁾ indicated that a significant relationship existed between 10-km run time and vV̇O_2max in a group of well-trained male runners. However, V_max is more closely associated with race pace in middle-distance events than to the slower velocities of longer distances and should present an optimal variable for middle-distance athletes to utilize in training.

Some ^{(1,5,9,10,12-14)} now argue that V_max describes the ideal training intensity when the goal is to run for as long as possible at V̇O_2max. Takayoshi ⁽¹⁶⁾ suggested that V_max can be used to predict velocity over 3000 m. These results support Morgan et al. ⁽¹⁴⁾, both claiming that v V̇O_2max can account for at least as much variance in distance running performance as blood lactate variables. Babineau and Leger ⁽²⁾ also indicate that V_max has a close relationship with performances from 1500-5000 m. They further advocate that utilizing aerobic intermittent training with a 5:1 effort to pause ratio can be easily applied to regular workouts and be used as an additional physiological monitor.

Hill and Rowell ⁽¹³⁾ claim the rationale for using V_max in exercise prescription is that, it is the lowest velocity at which V̇O_2max is elicited and it is necessary to achieve V̇O_2max to improve it. It is further suggested by Hill and Rowell ⁽¹²⁾ that using V_max should describe the ideal training intensity when the goal of training is to increase maximal aerobic power by training for as long as possible at V_max or by repeating shorter bouts at V_max with minimal fatigue.

A second variable closely related to the V_max is the T_max, which is defined as the time that V_max can be sustained. Billat et al. ^(5,9,10) showed that when using direct measurements of V_max, the average T_max, or time spent running at V_max ranges between 2 min 30 s and 10 min. Billat et al. ⁽⁵⁾ further suggested that direct measurement of this variable could be included in the assessment of the athlete and that in a laboratory setting the average value could be a reliable variable to be used with a group of subjects in studying the effects of training.

Hill and Rowell ⁽¹³⁾ eluded that T_max can be used in the prescription of repetition training or interval training at V_max, where V_max can be used to provide an individualized exercise intensity and T_max can be used to provide an individualized exercise duration. Hill and Rowell ⁽¹³⁾ found that there is no physiological rationale for the prescription of exercise at V_max for durations that are less than 60% of T_max if the intent of the training is to attain and maintain 100% of V̇O_2max. Findings from Hill and Rowell's study ⁽¹³⁾ indicated that the average subject was able to perform six repetitions at 60% T_max and spend the same amount of time at 95% V̇O_2max as in one exhaustive run but without having to run to exhaustion.

Babineau et al. ⁽²⁾, claims that intermittent exercise is a regular feature of an athletes training program, believing that it causes less disruption and is better tolerated than an all-out effort such as a time trial. The effort to pause ratios utilized is also an important consideration in setting interval training sessions. Babineau and Leger ⁽²⁾ highlight that most prevailing training programs for endurance sports use an effort to pause ratio of 1:1 or 1:2. Berthoin et al. ⁽³⁾ concluded that maximal aerobic speed, (V_max) was a pertinent criterion to set training intensities for aerobic training sessions. Their study findings indicated that one intense interval session per week, over a 12-wk period, was sufficient enough to moderately (6%) improve the V_max of initially untrained subjects. Furthermore, subjects in the intense-training group showed a greater improvement in their V_max than did their initially untrained counterparts.

High-intensity, intermittent training has been shown to be a very effective means of increasing maximal oxygen uptake ⁽¹⁵⁾. Due to the demands placed on the cardiovascular system during high intensity intermittent training, Tabata et al. ⁽¹⁵⁾ indicate that it is conceivable that it is not the exercise intensity per se but the high oxygen uptake that is usually found during high-intensity, intermittent training that results in the improved maximal oxygen uptake. Tabata et al. ⁽¹⁵⁾ further claim that it may be reasonable to assume that the high oxygen uptake obtained during some forms of intermittent training leads to the significant stress on the aerobic system and results in the large increase in V̇O_2max. Due to the relationship between V̇O_2max and vV̇O_2max, it is likely that the effects of training would be linear for both variables.

In using V_max as the running speed or exercise intensity, it can be assumed that over 95% of V̇O_2max will be utilized in an interval lasting greater than 60% of the subjects T_max, in accordance with Hill and Rowell's earlier findings ^(12,13). The purpose of this study, therefore, was to determine the effects of an individualized training program using V_max as the exercise intensity and utilizing between 60 and 75% of a subject's T_max as the exercise duration. The subject's pretraining and post-training V_max, T_max, and 3000-m time trial data were examined to determine the usefulness of using these parameters as exercise prescriptors.

METHODS

Subjects. Five middle-distance, trained athletes volunteered to participate in the study. They were well-trained, state-level athletes from local athletic and triathlon clubs. Subjects had the following characteristics (mean ± SD): age, 22.8 ± 4.5 yr; height, 181 ± 4.7 cm; weight, 74.1 ± 3.2 kg; skinfolds based on five areas, 35.4 ± 1.3 mm; max HR, 192 ± 4 b·min⁻¹; V̇O_2max was 61.5 mL O₂·kg·min⁻¹ ± 2.9, and individual V_max and T_max data were gathered for analysis. The study was approved by the institutional ethics committee and all subjects provided written, voluntary, informed consent. Subjects participated in a range of activities in their training, including long slow-distance work, speed work, tempo training, and over-speed efforts, as well as weight training.

Procedures. Each subject initially completed three V̇O_2max tests, which also determined V_max, three T_max tests, and a 3000-m time trial (TT) on a synthetic running track. These tests were run over a 2-wk time period in a random fashion. Subjects then undertook a 4-wk training program consisting of two high-intensity, interval-training sessions and one recovery run session per week. Subjects then undertook the same laboratory and field testing as before the pretraining sessions, which were again completed in a random fashion during the 2 wk following the training program. Laboratory data collection was carried out in the climate controlled (18-21°C) Human Performance Laboratory at the University of Tasmania whereas the 3000-m TT was carried out on a synthetic running track under consistent environmental conditions. Subjects were directed to be fully rested when reporting to the laboratory or for field testing and to have refrained from using caffeine-containing food or beverages, drugs, alcohol, cigarette smoking, or any form of nicotine intake 24 h before testing. They were also asked to refrain from eating large meals in the 4 h before any testing.

Experimental Protocols

Determination of V̇O_{2 max}and V_max. VO_{2 max} and V_max tests were measured using a velocity incremented progressive exercise protocol, on a Quinton Q65 treadmill (Quinton Instruments; Seattle, WA). The initial speed was set at 10 km·h⁻¹ for 2 min and was then incremented 2 km·h⁻¹ every minute, until a speed of 14 km·h⁻¹ were reached. Thereafter, the speed was increased in increments of 1 km·h⁻¹ every minute until subject exhaustion. The protocol ceased when the subjects pressed the emergency stop button or when they were unable to maintain the leg speed necessary to stay on the treadmill. The treadmill was calibrated before and after all testing.

To determine V̇O_2max, on line gas analysis was undertaken (Quinton Metabolic Cart, QMC). Subjects breathed room air through a Hans Rudolph 2700 valve (Kansas City, MO) that was linked via 3.5-cm tubing, to the mixing chamber of the QMC. The oxygen and carbon dioxide analysers were analyzed before and after each test session with alpha standard gases (BOC, Sydney, Australia) of two known concentrations (1 = 14.2% O₂ and 3.4% CO₂ and 2 = 18.4% O₂ and 5.1% CO₂). The Pneumotach was also calibrated before and at the end of the testing according to manufacturer's specifications using a 3-L syringe. The criteria for achieving V̇O_2max were two: volitional exhaustion, a heart rate within 5 b·min⁻¹ of predicted maximal heart rate (220 − age); or an increase in work rate with no accompanying increase in O₂ consumption.

V_max is defined as the lowest running speed that elicited an equal V̇O₂ to V̇O_2max. V_max was determined by recording the highest V̇O_2max value achieved by the subject and by noting the corresponding running velocity achieved by the subject. This is in line with previous work in this area in so much that it is the minimal velocity that elicits V̇O_{2 max}⁽¹¹⁾.

Determination of the time to exhaustion at V_max(T_max). The T_max tests consisted of a 15-min warm up that included a 5-min stage where the velocity was selected by the subject (approximately 8-9 km·h⁻¹), 5 min of stretching, and a further 5 min of running at 60% of V_max. The treadmill velocity was then increased to 18 km·h⁻¹, upon which time the subject remounted the treadmill and began running. Velocity was then increased to V_max within 10 s. Subjects were verbally encouraged by the investigators to run to exhaustion. The test ceased at volitional fatigue.

Determination of 3000-m TT. Each subject undertook a 3000-m TT on a synthetic athletic track composed of red polytan, which included rubber granules, black tack, and resin. This was completed as a self-paced individual effort to maintain individualized results within testing and training. The average speed sustained over the 3000 m was expressed in km·h⁻¹ and as a percentage of V_max.

The training program. Subjects completed a 4-wk training program consisting of two interval type sessions lasting approximately 60 min (8 in total: 5 intervals for any set at 60-65% and 6 intervals for any set at 70-75%) and one recovery run session that was run for 30 min at 60% of the subject's V_max. There were 12 sessions in total. Interval durations were derived by using manipulations of between 60 and 75% of subjects T_max, whereas interval intensities were based on subjects V_max velocity. All training sessions consisted of a warm-up, which included 5 min of jogging, where the initial velocity was selected by the subject. Subjects then stretched for 5 min and then resumed running at 60% V_max for another 5 min, after which time their warm-up was complete and subjects stepped off the treadmill. Treadmill speed was then increased to 18 km·h⁻¹, whereby the subject remounted and speed was increased to the subjects V_max within 10 s. The interval (%T_max) was then completed. All subjects wore a heart rate monitor (Sports Tester 4000, Polar Electro, Kempele, Finland) for the duration of each training session. Subjects' heart-rate values were recorded immediately before and after each interval session. The training program is summarized in Table 1.

TABLE 1: The 4-wk training program for each subject.

Subjects completed an active recovery for 5-10 min after all testing and training sessions and all tests were completed 2 d apart to allow subjects sufficient time to recover. All training was carried out on a Quinton Q 65 treadmill under the supervision of the investigators to ensure subject safety and compliance with the program.

Data analysis. The data was analyzed using Statview 4.0® computer program. Where necessary, data was analyzed by ANOVA or Student's t-test. Where an ANOVA was used, the Scheffé test was also used to indicate significant (P < 0.05) differences between groups.

RESULTS

The data in Table 2 shows the results of the 3000-m TT for each subject and the average speed during each of the time trials. The pretraining 3000-m TT was significantly (t₄ = 2.86, P < 0.05) slower (616.6 s) than the posttraining trial (599.6 s).

TABLE 2: Individual 3000-m time trials and average speed, pre- and post-training for each subject.

A comparison of the three pretraining trials indicated no significant differences (F[2,12] = 0.40, P > 0.7) and this was also true for the posttraining trials (F[2,12] = 0.1, P > 0.9). Table 3 illustrates the average (of the three trials) for V̇O_2max values for each subject. The mean pretraining V̇O_2max was 61.5 ± 2.9 mL O₂·kg·min⁻¹ as compared with the posttraining V̇O_2max of 64.5 ± 2.1 mL O₂·kg·min⁻¹. A comparison of the pretest and posttest results for all subjects indicates a significant (t₁₄ = 3.14, P < 0.007) increase due to the training.

TABLE 3: Average V̇O_2max values for each subject.

Table 4 shows the peak and average V_max values for each subject in km·h⁻¹. The peak posttraining V_max values are significantly higher than the peak pretraining V_max values (t₄ = 3.2, P < 0.03). The mean V_max pretraining values were 20.5 km·h⁻¹ as compared with the mean posttraining V_max value of 21.3 km·h⁻¹. The posttraining V_max values are significantly greater than the pretraining V_max values (t₄ = 4.0, P < 0.02).

TABLE 4: Peak and average V_max values pre- and post-training for each subject.

Table 5 represents the peak and average T_max values for each subject. The peak t max values pretraining were significantly lower than the peak T_max values posttraining (t₄ = 2.8, P < 0.05). When the mean T_max values for pretraining were compared with the mean T_max values for posttraining (225.5 s and 300.9 s, respectively), the posttraining values were significantly greater than the pretraining values (t₄ = 2.8, P < 0.05).

TABLE 5: Peak and Average T_max values pre and post for each subject.

The heart rates achieved by the subjects while undertaking the training program were consistent with high-intensity work. Heart rates varied from 181 ± 2 b·min⁻¹ to 189 ± 3 b·min⁻¹ for the two intensities of training program.

DISCUSSION

The main finding from this study, based on the results obtained when comparing pre- to post-training TT, V_max, and T_max data was that the utilization of V_max and T_max as exercise prescriptors is of benefit to the well-trained, middle-distance athlete. There was a wide range of both pre-training results: 3000-m TT, 550-702 s; average V_max, 18-22.67 km·h⁻¹; and average T_max, 204-291, as well as posttraining results: TT, 537-658 s; average V_max 19-23.67 km·h⁻¹; and average T_max, 235-387 s. The performance improvements in all subjects, however, were relatively uniform. The significance of these results indicates that the training program was successful in achieving a performance enhancing effect with all subjects in the study.

Previously, Hill and Rowell ⁽¹³⁾ indicated that their was no physiological rationale for the prescription of exercise at V_max for durations that are less than 60% of T_max, when the aim of training was to attain and maintain 100% of V̇O_2max. Findings from this study indicate that a rationale for the prescription of repetition training at V_max for between 60 and 75% of T_max provides a training intensity and range of durations that are sufficient to achieve significant performance improvements. We estimate that V̇O_2max was at or above 95% during each interval of all training sessions completed. It was not established whether V̇O_2max was obtained or maintained at 100% during each of the intervals, although it appeared likely that this occurred at intensities above 70% of subject T_max and during the final three intervals of all sessions completed.

Each subjects heart rate was monitored during the training sessions to try and gain an understanding of the intensity that they were able to maintain as a percentage of their maximum heart rate. Subjects achieved above 90% of their actual maximum heart rates (attained in the V̇O_2max test) during all training sessions. However, some interesting points were noted. The first was that at durations of 60 and 65% of T_max the heart rate could be maintained at approximately 90-95% of the actual maximum heart rate for the entire set of repetitions. The second was that at durations of 70 and 75% of T_max the heart rate could only be maintained at 90-95% of their maximum heart rate for approximately the first two or three repetitions after which subjects reached 100% of their actual maximum heart rate in each of the final repetitions. The third point noted was that once the subject's recovery heart rate did not recover to below approximately 125 b·min⁻¹ the next interval obtained a heart rate response of 100% of the actual maximum heart rate, this occurred almost exclusively across all subjects.

The other aspect of subject performances that was observed during each training session was that sessions of durations 70 and 75% T_max proved to be too intense for those subjects who had a V_max velocity of greater than 21 km·h⁻¹. The resultant fatigue induced by the V_max intensity inevitably resulted in a numbness or "lead"-like feeling within the legs due to the accumulation of lactic acid and muscle fatigue. It was interesting to observe that once subjects had achieved and maintained 100% of their actual maximum heart rate and successfully completed an interval, it became a mind game as to whether they would attempt completion of the following interval or hold back slightly and cease the interval, although above 97% of their actual maximum heart rate was achieved even if it was ceased, in a bid to attempt completion of the final interval of the session. The judgments of the subjects to "listen to their body" became a vital aspect of their training session along with an increased "mental toughness," and it is our opinion that this was a great benefit obtained from this form of training prescription.

Further benefits observed throughout the training period were improved breathing control and regulation. The subjects' focus on their breathing became more autonomous as the training period progressed, and it was a factor that may have assisted in delaying the onset of fatigue. The running technique of all subjects also improved significantly, we believe, due to the V_max velocity being used as the intensity. Subjects had to minimize any excess head movement or any lateral movements so that all their energy and movements were traveling along a forward plane and were being used more efficiently. It would be interesting to do further study on this aspect of the training program to ascertain whether or not this form of training can improve an athlete's overall running economy. Another important aspect that was derived from the training period was the ability of subjects to recover in between repetitions and at the completion of each session. All subjects commented that they felt like they were recovering better as the training period progressed and by the end of the training period all subjects were able to recover to 105 b·min⁻¹ after a 5-min active recovery period.

One pitfall of the study is the subjects being made to run at a constant velocity for a given time frame. It negates the real effects of pacing which occurs in performance or race situations and eliminates the distance factor, which many runners use to push themselves to the finish line. We attempted to minimize the effects of this by including a "real" individual performance situation into the testing stages, the 3000-m TT, so that subjects could gauge their improvement levels and put results in terms that were meaningful to them.

Other disadvantages that may be highlighted are the facilities and equipment required to implement such a program. However, Billat et al. ⁽⁸⁾ suggests a viable alternative that can be used on the training track that is relatively reliable. The advantages of this form of exercise prescription is that it takes place in a highly controlled environment, can easily be monitored and assessed, and allows for good feedback from the coach to the athlete.

Hill and Rowell ⁽¹³⁾ believe that training duration could be individualized based on each athletes time to achieve and time spent at V̇O_2max, although it is still not established whether sustaining 100% of V̇O_2max is necessary to elicit maximal improvements or whether merely achieving V̇O_2max may be important when training. It seems logical that these two parameters are carefully considered when prescribing a training program, as they may assist the rate of response of the aerobic system. We suggest from the results seen in this study, that the prescription of V_max as a training intensity and between 60 and 75% T_max as a training duration, provides a suitable training program that can be based on the unique needs of an athlete allowing them to develop at their own rate.

In summary, the purpose of the study was to determine the effects of a training program utilizing V_max as an exercise intensity and between 60 and 75% of T_max as an exercise duration. The important findings from the study were that there were significant improvements in all subjects' V_max, T_max, and individual performances in the 3000-m TT. A significant improvement was seen in all subjects' T_max, which we believe is a critical finding because, if athletes can prolong the onset of fatigue and maintain their top speed or V_max for as long as possible, then they will be far better equipped to run personal best times. The most significant improvement was in subjects' V_max, indicating that this type of training not only improves the ability of an athlete to withstand fatigue but also to increase their overall running velocity.

It is of our opinion that by utilizing between 60 and 75% of an athlete's T_max as an exercise duration and by using V_max as an exercise intensity that these two parameters can be extremely valuable tools in exercise prescription. The results obtained in this study were achieved using well-trained athletes, which has assisted in giving the results a greater level of reliability and validity. However, it is also recognized that there is far more research required before any sound conclusions can be formulated in this particular area of study.