High-resistance interval training improves 40-km time-trial performance

Original Research / Training
High-Resistance Interval Training Improves 40-km Time-Trial Performance in Competitive Cyclists Amy M Taylor-Mason Sportscience 9, 27-31, 2005 (sportsci.org/jour/05/amt-m.htm) Kinetic Edge Cycling, Box 25941, Auckland, New Zealand. Reviewer: Carl D Paton, Centre for Sport and Exercise Science, Waikato Institute of Technology, Hamilton, NZ. Interval training at race-specific high cadences improves endurance cycling performance, but there is evidence that adding resistance to reduce the ca-dence might be more effective. AIM. To determine the effect of high-resistance interval training on endurance performance of male cyclists during the competi-tion phase of a season. METHODS. In a randomized controlled trial, 10 cy-clists in a control group maintained usual training and competing while 12 cy-clists in an experimental group replaced part of their usual training with high resistance interval training twice weekly for 8 wk. Mean power in a 40-km simu-lated time trial, maximal oxygen consumption (VO2max), incremental peak power, body composition, and leg strength were measured before and after training. RESULTS. Relative to control training, there were clear beneficial effects of resistance training on 40-km mean power (7.6%, 90% confidence limits ±5.0%). There were also clear beneficial effects on incremental peak power (3.5%, ±4.2%), VO2max in ml.min-1.kg-1 (6.6%, ±7.0%), and sum of 8 skinfolds (-12%, ±11%). Effects on body mass (-1.6%, ±1.9%) and thigh mus-cle area (0.6%, ±2.7%) were possibly trivial. Effects on VO2max in L.min-1 and three measures of isokinetic leg strength were unclear, owing to large errors of measurement. CONCLUSIONS. High-resistance interval training produces a major enhancement in endurance power of athletes in the competitive season. The benefits of this form of training should transfer to competitive performance. Update 6Feb06: Correction to peak power in Table 2. INTRODUCTION
In a review published at this site last year, intensity training". They suggested that the Paton and Hopkins (2004) summarized the gains would probably be less if the high-evidence for beneficial effects of various kinds intensity training were performed in the com- of high-intensity resistance and interval training petitive phase, when athletes normally include on the endurance performance of competitive higher intensity training in their programs. In- athletes. Although the gains in endurance deed, in the only pervious training study per-power output on average were up to 8%, "all formed during the competitive phase of a sea- son (Toussaint and Vervoorn, 1990), sport- competitive phases of the athletes’ programs, specific resistance training enhanced competi- when there was otherwise little or no high- tive time-trial performance of swimmers by an amount equivalent to a useful but smaller ~2% were measured using skinfold calipers (Holtain, in power output. In a follow-up study, Paton UK). Maximal aerobic capacity (VO2max) was and Hopkins (2005) observed improvements of then measured using an incremental (ramp) 6-9% in various measures of endurance power. protocol with the subject's own racing bicycles Evidently, some forms of resistance training mounted on the Kingcycle ergometer (KingCy- can be very effective, even during a competitive cle, High Wycombe, UK), which was calibrated prior to each test. An initial workload of 100 W I was also interested in the benefits of resis- was increased 33 W each minute until volitional tance training for endurance performance, and fatigue. VO2 was measured from analysis of coincidentally performed a study on cyclists during the same competitive season that Paton Instruments, Pittsburgh Pa). VO2 was averaged and Hopkins performed their training study. over 20-s intervals. A computer interfaced with The outcome is the basis of this paper. the Kingcycle ergometer measured power throughout the test and peak power was defined as the highest mean power recorded over any Subjects
60-second period of the incremental test. Twenty-four well-trained male cyclists were recruited through Auckland cycling clubs. All Table 1. Subject characteristics, including baseline subjects provided informed written consent in performance and anthropometric measures for the accordance with the University of Auckland human subjects ethics committee. All subjects in the study were in the competition phase of their training and were free of injury and ill- ness. A description of the subject groups is shown in Table 1. Subjects were randomly assigned in to either an experimental high-resistance interval- training or a control normal-training group. Two subjects in the control group withdrew before the completion of the study. Subjects in the experimental group performed eight weeks of supervised high resistance interval training twice per week, in addition to their normal low intensity endurance training. The control group continued with their normal training programs which was a combination of high intensity rac-ing, and low intensity endurance training. All subjects were given detailed training logs to complete four weeks prior to, and during the eight week intervention period. All subjects repeated the testing procedures 4-10 d follow- Experimental Measures
Prior to testing, subjects were instructed to refrain from intensive training, caffeine, and alcohol for 24 hours, and to remain on their VO2max test using a Biodex isokinetic dyna- normal diet. This investigation was a pre-post mometer. The subject’s hip and knee angles design, thus the following procedures were were positioned to simulate top dead centre or conducted within one week pre- and one week the start of the power phase of the pedaling post-intervention. All testing procedures al- cycle as described by Faria and Cavanaugh lowed a minimum of 48 h recovery between (1978). The movement involved hip and knee tests. On the first visit to the laboratory, sub- extension to bottom dead centre or just prior to jects were weighed and sum of eight skinfolds full knee extension. Maximal repetitions at isokinetic leg speeds of 180, 270 and 360°.s-1 the estimate as 90% confidence limits and as (3.1, 4.7 and 6.3 radians.s-1) were performed chances the true effect was practically benefi- five times and peak torque was recorded as the cial and harmful. For calculation of the chances highest of the five values. These speeds equate of benefit and harm, the following values of to 30, 45, 60 revs.min-1 on the bicycle, which smallest worthwhile effects were entered into represent the range of cadences used in the the spreadsheet for each variable: 1.5% and high-resistance interval-training program. 0.65% for 40-km mean power and time respec- On a second visit to the laboratory, subjects tively (Paton and Hopkins, 2006); 1.5% for performed a 40-km cycling time trial on the Kingcycle ergometer. To ensure that subjects ratio (on the assumption that changes in these gave their maximum effort they were informed variables translate directly into changes in mean that they would receive incremental financial power in a time trial); and a standardized mean rewards if they completed the time trial at or difference of 0.20 for all other measures (Hop- above 70% of their individual peak power kins, 2003). Practical inferences were drawn measured on the first visit and post intervention using the approach described elsewhere in this incentives based on improvement. Subjects were permitted to consume fluids ad libitum Briefly, if chance of benefit and harm were both >5%, the true effect was assessed as unclear (could be beneficial or harmful). Otherwise, Training Intervention
Cyclists in the high resistance interval train- quantitative chances of benefit or harm were ing group performed prolonged rides in the assessed qualitatively as follows: <1%, almost laboratory twice per week, during which low certainly not; 1-5%, very unlikely; 5-25%, cadence (40–80 revs.min-1) intervals were per- unlikely; 25-75%, possible; 75-95%, likely; 95- formed as suggested by Polishuk (1994). All 99, very likely; >99%, almost certain. Each interval training sessions were supervised by spreadsheet also calculated a standard deviation the primary investigator. Sessions consisted of representing individual responses to the treat- 5-6 intervals of 3 to 22 minutes, and the total ment (typical variation about the mean effect interval duration per session increased steadily from subject to subject) and another standard deviation representing the typical error of Week 8. Rest periods in between work intervals measurement in the control group between pre ranged from 1 to 5 minutes. Cadence was set with a metronome. Subjects pedalled to the set cadence using the highest gear on their bicycles There was little difference in mean charac- and graded resistance on the simulators to teristics and baseline performance in the two maintain the highest power output for the ca- groups (Table 1). The main effect of the inter- dence. Average and maximum heart rate were vention period was a substantial enhancement recorded using heart rate monitors (Polar, of performance in the 40-km time trial, due Kempele, Finland). Power output in Watts was mainly to an enhancement in the experimental manually recorded from the Cateye simulators group and a relatively small impairment in the every minute during the work intervals. Due to control group (Table 2). The nett effect on small but consistent differences in ergometers (Cateye and Kingcycle), power output was then pressed relative to body mass but a little smaller re-calculated to give an approximation of King- and unclear when expressed in absolute units. cycle power output in Watts from the regression The experimental group also experienced a substantial reduction in skinfold thickness rela-tive to the control group, but changes in body Statistics
Each dependent variable was analyzed with mass and mid-thigh muscle area were more a published spreadsheet that used log transfor- likely to be trivial. The isokinetic testing pro- mation to estimate the effect of training as the difference in the mean percent change between Standard errors of measurement for the con- the experimental and control groups (Hopkins, trol group between pre and post tests were: 40- 2003). Each spreadsheet provided precision of km time-trial time, 1.7%; 40-km time-trial mean power, 4.3%; incremental peak power, km time-trial mean power was 4.4%, but the VO2max (L.min-1), 7.5%; body mass, 1.8%; 90% confidence limits were -5.2% to 8.4%. sum of 8 skinfolds, 11%; mid-thigh muscle About half the measures had negative standard area, 2.3%; and peak torques, 8-11%. The 90% deviations for individual responses (owing to confidence limits for the true values of the error greater variation in the change scores in the of measurement were ×/÷1.5 for all measures. control group), but the confidence limits all Standard deviations representing individual allowed for the possibility of substantial real responses had too much uncertainty for any firm conclusions; for example, the value for 40- Table 2. Effect of 8 weeks of high resistance interval training on cycling performance, physiologi- Performance measures
40-km time-trial mean power
Physiological and anthropometric measures
VO2max (L.min-1)
±90%CL: add and subtract this number to the mean effect to obtain the 90% confidence limits aBased on the following smallest worthwhile changes in performance: 1.5% for 40-km mean power, peak power at VO2max, VO2max, and power-to-weight ratio; 0.65% for 40-km time; standardized mean difference of 0.20 for all other measures. bData shown after deletion of one control subject who showed a decline in performance of 10% DISCUSSION
The main finding of this investigation was that eight weeks of low-cadence high-resistance study and most other previous studies is that the interval training improved mean power by ~8% improvements occurred during the competition in a 40-km time trial in well-trained male cy- phase of a racing season, when the athletes clists. Furthermore, these improvements oc- were already training and competing at high curred during the competition phase of the rac- intensity. Inasmuch as the smallest worthwhile ing season, when the cyclists were already increase in performance for an elite cycling training and competing at high intensity. The time-trialist is ~1.5% (Paton and Hopkins, improvements, and those in incremental peak 2006), the gains I have observed represent ma- power and VO2max, are similar to those in jor enhancements. Only two other published most previous studies of high-intensity interval studies of effects of high-intensity training on and resistance training, when the uncertainty in endurance athletes have been performed during all the estimates is taken into account. a competition phase. The enhancements in my study were greater than the ~2% observed in a that measures derived from isokinetic ergome- study of swimmers (Toussaint and Vervoorn, try are too noisy to be useful for tracking 1990), possibly because the low-cadence train- ing I achieved with the cyclists was more effec- Although my study was aimed primarily at tive than the protocol devised for the swim- determining the effect of resistance training on mers. The gain I observed in peak incremental endurance performance, I measured several power was possibly less than the 6% Paton and physiological and anthropometric variables that Hopkins (2005) observed with cyclists, but their are potentially related to the mechanism of the gains in shorter endurance tests (8-9% in 1-km effect. It is clear that an increase in VO2max and 4-km time trials) were similar to what I could be the main reason for the increase in observed in the 40-km time trial. Their resis- endurance performance, but I can only specu- tance-training sets were similar to ours, but they late that an enhancement of economy was also included sets of ballistic jumps. The contribu- involved, as in other studies of the effects of tion of the jumps to performance enhancement resistance training on endurance (Paton and Hopkins, 2004). A contribution from the other Some of the measures of performance in the component of endurance, fractional utilization present study produced unclear outcomes. The of VO2max, is another possibility. An increase problem appears to have been relatively large in body mass could be harmful for cyclists errors of measurement for those measures. The when the course includes hill climbing. Resis- errors for 40-km mean power, VO2max, and tance training can increase body mass by in- peak power were twice as large as reported in creasing muscle mass, but my training protocol some reliability studies (Hopkins et al., 2001). appeared to have little effect on thigh muscle The errors in the present study probably reflect mass, and the only change in body mass was real individual variation in performance of the trivial. The loss of skinfold thickness is in cyclists in the control group over the time frame principle a benefit, but only if it represents a of the study. There was probably also a substan- substantial loss of body mass. Whether the loss tial contribution of technical (equipment) error of skinfold thickness was a direct effect of re- to the unacceptably large error of measurement sistance training or an indirect effect of a for VO2max. I agree with Hopkins et al. (2001) REFERENCES
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