Training

High Rep Strength Training

A New Training Paradigm

You may be familiar with the old adage – heavy weights / low reps build strength & size, light weights / high reps build endurance.  This belief about the effects that different numbers of repetition have on the body has been repeated for many, many years.  I started lifting weights in 1982 and it was accepted as truth at that time.  This belief is even accepted wisdom in the exercise physiology community.  The exercise physiology textbook in my library, published in 1996, states, “Performing an exercise between 3-RM (repetition maximum) and 12-RM provides the most effective number of repetitions for increasing muscular strength.”(1)  The bottom line is that there is little to no debate as to the effect different numbers of repetitions have on the body.  If you want to increase strength and size, heavy weights and low reps is the universally agreed upon prescription. 

From a practical perspective this has resulted in most or all resistance training programs recommending heavy weights and low reps exclusively.  Basically every strength training or bodybuilding program recommends repetitions of 20 or less.  During 15 years of following popular strength training literature I can recall only 2 instances where reps higher than 20 have been discussed and in only one of those instances was it even seriously recommended as a viable training method. 

In the first case, in the early 1980s or so a professional bodybuilder (Johnny Fuller, if my memory serves me correctly) revealed that he preferred to train using 32 repetitions for most or all of his exercises.  At the time this was used as an example of the recommendation that each trainee needs to find what works best for him/her, but I don’t recall that the article recommended such high reps for anyone else.  Nor did any follow on articles I ever saw suggest that trainees might experiment with reps in that high range.

In the second case, Muscle and Fitness magazine ran a few articles in the late 1980s about 100 repetition training.  This series was run after one bodybuilder in particular revealed that he used 100 reps for brief training periods a few times a year.  After that series of articles, I don’t recall ever hearing about this type of training again. 

So, while the adage says heavy weight/low reps build strength and light weights/high reps build endurance, I do not believe that high rep strength training is commonly used or seriously considered as a viable training method by most trainees or their coaches.  It isn’t commonly recommended to those who are most interested in increasing strength and/or size, nor does it seem to be a part of the serious endurance athletes training methods.

Since the adage says light weights / high reps building endurance, and increasing endurance is a goal of endurance athletes, I began wondering why high rep strength training was not commonly used by endurance athletes.  Power Running teaches that muscle power is the primary determinate of endurance performance.  The person with the greatest power output is the one who wins the race.  If you want to improve your performance, you must increase your power output.  If you are faster today than you were yesterday I guarantee you that your power output has increased.

This naturally leads us to the question, what determines muscle power output in the first place?  I’ve written on this topic previously and have posted the articles to my web site for those who want more detail (2), but in a nutshell there are three primary muscle factors that combine to determine power output – rate of contraction, force, and resistance to fatigue.  The faster a muscle fiber contracts, the more force it produces during contraction, and the longer period of time it can contract before fatigue sets in, the more power that muscle can produce.

An increase in force output is just a fancy way of saying that the muscle got stronger.  The adage says heavy weights / low reps build strength.  The reason strength training is believed to be beneficial for runners is that it increases the amount of force produced during contraction, resulting in an increase in power output and, presumably, endurance performance.

What about the second part of the adage though?  The part that says light weights / high reps build endurance.  One of the muscle factors contributing to power output is fatigue resistance.  Increased resistance to fatigue is just another way of saying that the muscle’s endurance increased.  I reasoned that if high rep resistance training really did increase endurance, perhaps it might be a beneficial training method for endurance athletes.  With that thought in mind, I started searching the available research to see what had been done on this topic.  I found some exciting and surprising research for us to review.  Let’s get to it.

Heavy weight/low rep vs. medium weight/medium rep vs. light weight/high rep

The first thing I wanted to know was whether research supported the belief that heavy weights / low reps builds strength and that light weights / high reps build endurance.  After all, it wouldn’t be the first time that someone discovered that conventional wisdom was not completely accurate.  So, I thought it best to be sure. 

The classic research on this topic was conducted by Thomas DeLorme in 1945 (3).  DeLorme’s research indicated that heavy weights do indeed build strength while higher reps build endurance.  DeLorme is even credited with the axiom that heavy weights / low reps build strength and high reps / light weights builds endurance.  Quite a few other research studies on this topic have supported DeLorme’s findings, hence the reason it is now accepted as conventional wisdom.

This is not to say that DeLorme’s original axiom has gone unchallenged though.  Several research studies (4,5) that have found that the primary adaptation to either high or low reps is an increase in muscular strength.  So, even though it is accepted today that heavy weights / low reps builds strength and light weights / high reps builds endurance, the fact is that some research has challenged this belief, suggesting that high reps primarily build strength, not endurance and resulting in conflicting data on the topic.

In 1982 two researchers from the University of Kentucky set out to resolve this conflict (6).  Specifically, they wanted to determine the effects of three different resistance training protocols – heavy weights / low reps (6-8 reps), medium weight / medium reps (30-40 reps), and light weights / high reps (100-150 reps). 

They recruited forty-three untrained, healthy subjects and trained them with the bench press exercise three times per week for nine weeks with one of three training protocols.  The low rep group performed 3 sets x 6-8 reps maximum, the medium rep group performed 2 sets x 30-40 reps maximum, and the high rep group performed 1 set x 100-150 rep maximum.  Resistance was adjusted as needed to ensure each subject stayed in the appropriate rep range through the training program.

Before training began each subject was tested for their individual 1 rep maximum (1-RM), relative endurance and absolute endurance.  Relative endurance was determined by the maximum number of bench press repetitions they could complete with 40% of their 1-RM and adjusted as 1-RM changed, while absolute endurance was measured by how many reps could be completed with 27.23 kilograms.

At the end of the study all subjects were tested again for maximum strength, relative endurance, and absolute endurance.  All three groups improved maximum strength and absolute endurance.  The heavy weight / low rep group decreased in relative endurance while the other two groups increased relative endurance significantly.  The results of this study are shown in table 1.

Table 1:  Percent changes in max strength, absolute endurance, and relative endurance following strength training at three distinct repetition ranges

As can be seen from the data in table 1, the results of this study support DeLorme’s axiom.   Heavy weight / low reps do build strength, while light weights / high reps build endurance.  However, in contrast to DeLorme’s axiom, note that all 3 rep ranges resulted in increases in maximum strength.  And all 3 rep ranges resulted in increases in endurance, with the exception of the relative endurance of the low rep group.  So, while low reps increase maximum strength more than do high reps, and high reps increase endurance more than low reps the point is that resistance training significantly increases both strength and endurance.  The researchers commented on this same point.

“The reader should note, however, that with the exception of the relative endurance task for the high resistance low repetition group, all training protocols demonstrated significant improvements on each of the three criterion tests.”

Anderson and Kearney’s research went a long way to resolving the conflicting data on DeLorme’s axiom – heavy weights increase strength the most, high reps influence endurance the most, but all resistance training results in improvements in both strength and endurance.

In 1994 Stone and Coulter modeled a study after Anderson and Kearney’s study with the exception of using a less extreme rep range for the high rep group (7).  Stone and Coulter had their subjects perform either 3 x 6-8 reps, 2 x 15-20 reps, or 1 x 30-40 reps.  The results of this program supported the findings of Anderson and Kearney.  Strength and absolute endurance increased for all three groups.  The low rep group improved strength more than the other 2 groups and the high rep group improved endurance more than the lower rep groups.

The bottom line is that while DeLorme’s basic axiom is generally supported by this research, the fact is that resistance training results in improvements in both strength and endurance but to varying degrees depending on how many repetitions are performed.

What about alternating rep ranges?

The studies cited above have compared one rep range to another, high reps vs. low reps for example.  What about programs that include more than one rep range?  In 2004 a group of researchers tackled this very question in a fascinating study of varying combinations of high and low rep training (8).  This group speculated that a combination type program that included both low and high reps would be more effective than a periodized program consisting of single repetition scheme during each training period or phase.

To test their hypothesis they recruited 17 untrained subjects, divided them into two groups, and then trained each group twice per week for 10 weeks.  Subjects were tested for maximum strength and muscular endurance pre- and post-training.  The first 6 weeks of training was designated as phase 1 and both groups trained exactly the same during this phase. Workouts consisted of two exercises (leg extensions & leg presses) for 3 sets x 10-15 reps.  At the end of this first phase of training there was no difference between the groups; both had significantly and equally improved strength and endurance.  This is not surprising since both groups trained exactly the same during phase 1. 

During the final 4 weeks of the study, both groups conducted 5 sets x 3-5 reps of each exercise.  One group, the combi-type group, added a single set of 25-35 reps following their final low rep set.  At the end of the training program the combi-type group had increased their strength significantly more than did the other training group (14.7% vs. 9.3% respectively).  The results are displayed in table 2.

Table 2:  Set and rep ranges for 2 training phases and percent change in strength following phase 2.

In their discussion of these findings, the researchers wrote,

“This suggests that the combi-type regimen caused a larger increase in dynamic muscular strength than did the strength-type regimen when combined with the hypertrophy-type regimen in a periodized fashion… This effect appears to be inconsistent with the classical principle operating in resistance-exercise training, in which low-repetition protocols are used for muscular strength and low-intensity, high-repetition protocols are used for muscular endurance.  Sensible combinations of high- and low-intensity protocols may therefore be more important to optimize the strength adaptation to resistance training.”

There were also significant differences in endurance between the two groups.  During phase 1 both groups increased endurance with no significant difference in the percent change.  However, the combo type group’s endurance continued to increase during phase 2, while the strength type group’s endurance decreased 4.2%.  The results are displayed in table 3.

Table 3:  Percent change in endurance following each phase of training and total percent change in endurance.

In summary, this study found that a combination program consisting of heavy weights / low reps and light weight / high reps was more effective for improving both strength and endurance than a traditional periodized training program consisting of a single rep range during each training phase.  This is truly a fascinating finding.

High rep training’s effect on running / cycling performance

Strength training research studies often measure endurance and changes in endurance via resistance training, i.e. how many reps can be performed with a light amount of weight in a particular resistance exercise.  I term this “resistance exercise endurance”.  However, endurance athletes are more concerned with changes in endurance during traditional endurance exercise, running and cycling for example.  Therefore, the question to address is whether resistance exercise improves endurance performance in traditional endurance exercise or is it limited to resistance exercise endurance only.  I reviewed most of the available research on this topic in the article Resistance Training for Runners and found that resistance training had either a neutral or positive effect on endurance performance during traditional endurance exercise.  In no cases did strength training cause a decrease in endurance performance. 

One thing I didn’t consider in the article Resistance Training for Runners is if high rep strength training might have a more profound effect on endurance performance during traditional endurance exercise than low rep / heavy weights.  In light of the data we revealed above, that high rep training improves endurance more than low rep training, I decided to review the research to see if I could determine the effects of high rep strength training on traditional endurance exercise.  For purposes of my investigation I defined high reps as consisting of 20 or more reps.

Hickson et al (9) conducted a study employing sets of 5 reps for the quadriceps and hamstrings and 20 reps for the calves of untrained subjects.  This study found a 47% increase in short term (4-8 minutes) cycling performance and a 12% improvement in short term running performance. 

Hickson et al (10) repeated his first study but used trained endurance subjects who were already at a steady-state level of performance.  In this study he found improved short term cycling and running performance of 11% and 13% respectively.  He also found long term (1-1.5 hours) cycling performance improved by 20%.  The results on changes in 10k performance were inconclusive due to strength related injures incurred by 2 subjects that prevented them from completing the post run test.  Of the remaining six subjects, average 10k time improved by 44 seconds (from 42:25 to 41:430), an improvement not reaching the level of significance.

Hickson’s studies are not a true test of either low or high rep strength training since the upper leg muscle groups were trained with low reps while the calve muscles were trained with high reps.  There is no real way to distinguish which, if any, improvements were due to the low reps and which, if any, are due to the high reps.  However, since both studies included both high and low reps, I thought it appropriate to include them in this section.

Marcinik et al (11) had subjects perform 3 sets x 15-20 reps for the muscles of the lower body and measured an improvement of 33%, or 8.8 minutes, in medium term (26-35 minutes) cycling.  This particular study indicates that high rep strength training does positively affect endurance performance at competitive distances/time.

Paavolainen et al (12) had well trained subjects perform lower body explosive strength training exercises of 5-20 reps, 30-200 contractions per workout, and traditional leg circuit training exercises of “dozens” of reps. (An explanation of “dozens” is not offered, so I assume it means at least 2 dozen, or 24 reps, minimum for each exercise.)  Of these 2 exercise protocols the one most applicable to our discussion is the explosive strength training, which would be considered high rep training.  As a result of this training, subjects improved 5k time a significant amount (from about 18:30 to about 17:45 min:sec).

Campos et al (13) had subjects perform one of three rep ranges – 4 sets x 3-5 reps, 3 sets x 9-11 reps, or 2 sets x 20-28 reps - and measured changes in endurance by having the subjects cycle to exhaustion on a cycle ergometer.  At the end of the 8 week study all three groups improved maximal strength but only the high rep group significantly improved cycle time to exhaustion, from 7.6 minutes to 9.1 minutes.  The researchers noted that “the high rep group…appeared better adapted to for submaximal, prolonged contractions, with significant increases after training in aerobic power and time to exhaustion.”

The data from these 5 studies are summarized in table 4.

Table 4:  Summary of research examining high rep strength training on endurance performance.

These five studies are the only ones I could find that used high rep training to test for changes in endurance performance during traditional endurance exercises and, as shown in the table 4, all five studies resulted in improved endurance performance.  Additionally, I could find no other studies that showed a neutral or negative result on endurance performance.  In summary, the evidence supports my hypothesis that high rep strength training could significantly improve endurance performance during traditional endurance exercise, at least for running distances of up to 10k and cycling times of up to 1.5 hours. 

Low rep training’s effect on running / cycling / skiing performance

Okay, it’s pretty exciting that high rep strength training could be a significant booster of endurance performance.  Does this mean low rep strength training doesn’t improve endurance performance or that it’s not as good as high rep training?  That’s the next question I sought to answer.  So, I dug up all the research on changes in endurance performance from low rep training that I could find.  We already know from the research presented in the first section of this paper that low rep training improves resistance exercise endurance, so the question to address was whether it also improved traditional endurance exercise performance.

Hickson et al (9) conducted a study employing sets of 5 reps for the quadriceps and hamstrings and 20 reps for the calves of untrained subjects.  This study found a 47% increase in short term (4-8 minutes) cycling performance and a 12% improvement in short term running performance. 

Hickson et al (10) repeated his first study but used trained endurance subjects who were already at a steady-state level of performance.  In this study he found improved short term cycling and running performance of 11% and 13% respectively.  He also found long term (1-1.5 hours) cycling performance improved by 20%.  The results on changes in 10k performance were inconclusive due to strength related injures incurred by 2 subjects that prevented them from completing the post run test.  Of the remaining six subjects, average 10k time improved by 44 seconds (from 42:25 to 41:430), an improvement not reaching the level of significance.

Hickson’s studies are not a true test of either low or high rep strength training since the upper leg muscle groups were trained with low reps while the calve muscles were trained with high reps.  There is no real way to distinguish which, if any, improvements were due to the low reps and which, if any, are due to the high reps.  However, since both studies included both high and low reps, I thought it appropriate to include them in this section too.

Bishop et al (14) had endurance trained female cyclists perform 5 sets x 2-8 reps squats for 12 weeks.  One third of the sets were conducted at 2-4 reps, one third at 4-6 reps, and one third at 6-8 reps.  In essence, then, Bishop had this group mostly training with very heavy weights.  He assessed changes in endurance performance by measuring total power output during a 1-hour cycling test.  The subjects significantly increased maximal strength but there was only a small improvement in endurance performance, an improvement that did not reach the level of significance. 

Bishop and Jenkins (15) had untrained subjects train for six weeks, 3 times per week with 3-6 sets x 1-15 reps and found no improvement in time to exhaustion at critical power.  I don’t have access to the full-text of this study so I can’t comment definitively on it.  I speculate, though, that with a rep range of 1-15 that Bishop may have had subjects using very heavy weights for a significant portion of this study, as he did in his first study. (Note: If you have access to this full-text study, please contact me with the details of both the training program and Bishop’s discussion of time to exhaustion at critical power.)

Hoff et al (16) trained regionally competitive female cross country skiers with 3 sets of 6 reps on a specially designed apparatus designed to simulate the movement pattern of the arms in classic double ski poling (arms can provide a significant part of the propulsion during cross country skiing).  Hoff then assessed changes in endurance on a ski ergometer and found a 136.5% increase, from 6.3 minutes to 12.3 minutes, in time to exhaustion.  It is important to note that most resistance exercises do not mimic movement patterns used during the actual endurance event as closely as the apparatus used in this study.  It is unknown what effect the similarity between the movement patterns of the resistance exercise and actual competition may have had on these results.  I speculate that the use of this apparatus resulted in increases in both general and specific strength, which account for the very large improvements experienced by these subjects.

Campos et al (13) recruited thirty-two untrained men and divided them into 4 groups – a control group, a low rep group (4 sets x 3-5 reps), a medium rep group (3 sets x 9-11 reps), and a high rep group (2 sets x 20-28 reps).  Subjects trained three different exercises (squat, leg press, leg extension) for 8 weeks, twice per week for the first 4 weeks and then three days per week for 4 weeks.  In addition to measuring strength and muscular endurance pre- and post-training, aerobic performance was also measured pre- and post- training with a cycle ergometer.  There was no change in cycling performance for either the low rep (3-5) group or the intermediate rep (9-11) groups.  The high rep (20-28) group improved short term cycling performance significantly.

Izquierdo et al (17) trained elderly, non-exercising men (ages 65-74 years) twice per week for 16 weeks.  During the first 8 weeks the subjects trained 3-4 sets x 10-15 reps and during the final 8 weeks with 3-5 sets x 5-6 reps.  This group of elderly men improved their performance 10% during a cycling test to exhaustion.

Izquierdo et al (18) conducted a repeat of his earlier study but used untrained middle aged (ages 40-47) men as subjects.  As in his earlier study, subjects trained twice weekly with 3-4 sets x 10-15 reps for the first 8 weeks and then 3-5 sets x 5-6 reps for the final 8 weeks of the study.  As in his earlier study, Izquierdo measured a 10% increase during a cycling test to exhaustion.  Interestingly, all of the improvements in endurance performance occurred in the first 8 weeks of the study and no further improvements occurred during the final 8 weeks of the study.

The results of these 8 research studies are summarized in table 5.

Table 5: Summary of research examining low rep strength training on endurance performance.

What are we to conclude from these 8 research studies on the effects of low rep strength training on traditional endurance performance?  Well, first we see that of the nine groups studied five groups improved performance while four groups did not.  While the majority of groups studied show an improvement in performance, the presence of a significant number of studied groups finding no improvement in performance illustrate that more research needs to be conducted on this topic.

Second, and most interesting, of the five groups that improved performance, four of them employed either a combination of both low and high reps (both of Hickson’s studies used 20-25 reps in 1 exercise) or reps near the high end of the scale (both of Izquierdo studies used up to 15 reps for half of the study period).  One study (Bishop and Jenkins) had a rep range of 1-15, but the full details are not available and so I speculate, based on Bishop’s other study, that a significant portion of this study employed very heavy weights and low reps.  Only one study using low reps exclusively (Hoff et al) resulted in an improvement in endurance performance.  Note that the resistance training used in this study closely mimics the movement pattern of the actual competitive event which may have provided a unique training stimulus not available from other traditional strength training exercises.

What Does All This Mean?

What are we to make of all this data on low and high rep strength training and endurance performance during events such as running or cycling?  Let’s review.  Every study that has examined changes in traditional endurance exercise performance following high rep strength training has found an improvement in performance.  Conversely, only five of nine studies examining changes in traditional endurance exercise performance following low rep strength training have revealed an improvement in performance.  Four of those five studies have either used a combination of low and high reps or has used reps near the high end of the range.  Only one study using low reps has resulted in an improvement in traditional endurance exercise performance and the unique strength training apparatus used in this program may have amplified the results.

Based on this data, I suggest that the evidence supports that high rep resistance training may be a superior training method for endurance athletes than a more traditional lower-rep strength training program.  While I’d like to see more research on this topic, in the meantime, this data is enticing enough that I recommend that runners should give either high rep strength training or a combination of low rep / high rep training serious consideration.

If you decide to try high rep strength training, how many reps should you do?  I recommend training with at least 20 reps, but I suspect that higher reps, in the range of 35-50, might work even better.  I speculate that very high reps, in the range of 75-100, could also be quite beneficial.  This is just speculation on my part though, since I’m not aware of any data examining the effects of very high reps on endurance performance during traditional endurance exercise.

I’d suggest that a combination type program be used, with some sets consisting of heavy weights / low reps in the 10-15 rep range and some sets of lighter weights / higher reps in the 25-35 rep range.  I’d even go so far as to suggest experimenting with alternating very high reps of 75-100 with reps in the two lower ranges.

Summary

The old adage is that heavy weights / low reps build strength while light weights / high reps build endurance and a review of the research shows that the adage is basically true.  However, while that adage is basically correct, it does not reveal the complete picture.  All rep ranges, at least up to 150 repetitions, increase strength, but the lower rep ranges increase it more.  Endurance, as measured by resistance exercise, is also generally increased via resistance training, with as few as 6 reps causing an increase in endurance during resistance exercise.  It seems that 6 reps are minimally required to increase endurance with higher reps increase endurance significantly more than do the lower reps. 

A combination of both high and low reps has been shown to increase both strength and endurance more than a traditional lower-rep, periodized type training program.  For those who are most interested in maximizing muscular strength and size this finding is significant and should be seriously considered when designing a strength training program.

A review of the research indicates that high rep (20 reps or more) strength training has been shown to significantly improve endurance performance during traditional endurance exercises such as running, cycling, and cross country skiing.  The effectiveness of low rep strength effects on traditional endurance exercise performance is in conflict – only slightly more than half of the groups studied show an improvement in performance, while the others do not.  A careful examination of the low rep studies indicates that of those that resulted in an improvement in performance all but one either employed both low and high reps or used reps near the high end of the range.  I suggest this data supports my belief that higher reps are more effective for improving endurance performance than are lower reps.

Is high rep strength training a significant but overlooked performance booster?  A review of the data suggests it is.

Reference:

1.  Katch, Katch, McArdle, Exercise Physiology, Energy, Nutrition, and Human Performance, 1996, Williams & Wilkins, pg. 427

2.  Muscle Limit Performance, Muscle Contractility

3.  DeLorme, Thomas L., Restoration of muscle power by heavy resistance exercise, Journal of Bone and Joint Surgery, 1945, 27:645-667.

4.  Stull G, Clarke D., High-resistance, low-repetition training as a determiner of strength and fatigability, Research Quarterly, 41(2), 189-193

5.  Clarke D, Stull G., Endurance training as a determinant of strength and fatigability, Research Quarterly, 41(1), 19-26

6.  Anderson T, Kearney J., Effects of Three Resistance Training Programs on Muscular Strength and Absolute and Relative Endurance, Research Quarterly for Exercise and Sport, 1982, 53:1, 1-7.

7.  Stone WJ, Coulter SP., Strength/endurance effects from three resistance training protocols with women, J Strength Cond Res 8:231-234.

8.  Goto K, Nagasawa M, Yanagisawa O, Kizuka T, Ishii N, Takamatsu K., Muscular Adaptations to Combinations of High- and Low-Intensity Resistance Exercises, J Strength Cond Res, 2004, 18(4), 730-737.

9.  Hickson, R., Rosenkoetter, M., Brown, M.: Strength training effects on aerobic power and short-term endurance; Med. Sci. Sports Exerc., 1980, 12(5), 336-339

10.  Hickson, R., Dvorak B., Gorostiaga, E., Kurowski, T., Foster, C.: Potential for strength and endurance training to amplify endurance performance; J. Appl. Phsiol., 1988, 65(5), 2285-2290

11.  Marcinik, E., Potts, J., Schlaback, G., Will, S., Dawson, P., Hurley, B.: Effects of strength training on lactate threshold and endurance performance: Med Sci Sports Exerc., 1991, 23(6), 739-743

12.  Paavolainen, L., Kakkinen, K., Hammalainen, I., Nummela, A., Rusko, H.: Explosive-strength training improves 5-km running time by improving running economy and muscle power: J. Appl. Physiol., 1999, 86(5), 1527-1533

13.  Campos G, Luecke T, Wendeln H, Toma K, Hagerman F, Murray T, Ragg K, Ratamess N, Kraemer W, Staron R., Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones  Euro J Appl Physiol 2002, 88:50-60

14.  Bishop, D., Jenkins, D., Mackinnon, L., McEniery, M., Carey, M.; The effects of strength training on endurance performance and muscle characteristics; Med Sci Sports Exerc., 1999, 31(6), 886-891

15.  Bishop, D., Jenkins DG.: The influence of resistance training on the critical power function and time to fatigue at critical power.: Aust J Sci Md Sport, 1996, 28(4), 101-5

16.  Hoff J, Helgerud J, Wisloff U., Maximal strength training improves work economy in trained female cross-country skiers, Med Sci Sports Exerc, 1999, 31(6), 870-877.

17.  Izquierdo M, Ibanez J, Hakkinen K, Kraemer W, Larrion J, Gorostiaga E., Once Weekly Combined Resistance and Cardiovascular Training in Healthy Older Men, Med Sci Sports Exerc, 2004, 36(3), 435-443.

18.  Izquierdo M, Hakkinen K, Ibanez J, Kraemer W, Gorostiaga E., Effects of combined resistance and cardiovascular training on strength, power, muscle cross-sectional area, and endurance markers in middle-aged men.  Eur J Appl Physiol, 2005, 94, 70-75