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Tuesday, September 27, 2011

Weight Training Methods for Muscular Endurance

While lifting for 12-15 reps at approximately 60% 1RM is great for developing localized strength and endurance within specific muscle groups, there are other methods just as effective at improving muscular endurance.  If you lift regularly with minimal to no professional supervision, I recommend avoiding method #1, heavy weight training.  Same recommendation follows for variable load training unless you decrease the load. 
  1. Heavy weight training
    • 80-90% 1RM, 4-8 repetitions.
    • 100% 1RM produces the greatest improvements in both endurance and strength, but greatly increases risk of injury.
  2. High repetition training
    • 30-50% 1RM, 30-50 repetitions, 3-4 sets
    • May be used to develop power.  Reps and sets may stay the same, but use a load of 30% 1RM for optimal power development.  Full rest between sets is required.
    • A variation of this set to a time limit (interval training)
  3. Variable load training
    • Combines both methods.  Progressively lower loads are lifted consecutively with little to no rest.  Repetitions depends on the load.
    • First load focuses on strength- 66% 1RM or higher
    • Last load focuses on lactic acid production- 30-50% 1RM
1. HEAVY WEIGHT TRAINING:  Contrary to popular belief, lifting heavy weights for a few repetitions will not just improve muscular strength, it will also improve endurance.  Lifting heavy weights will improve endurance because all motor units must be recruited to complete the lift, that means both fast and slow twitch muscle fibers will be activated (2,7).  For this reason, it is widely accepted that there is a strong relationship between muscular strength and endurance (1,2).

I was skeptical about this method at first, but it made sense after I realized that the physiological changes that occur with heavy weight lifting are similar to that of endurance training.  The structural changes that occur with heavy weight training include increased number/ size of myofibrils, number of actin/ myosin and the size/ strength of tendons, ligaments and connective tissue (2,4).  In addition to these anatomical changes, anaerobic metabolism also improves through increased levels of creatine phosphate, glycogen and creatine phosphokinase (4).  All of these changes allow the muscle to operate with less effort to do the same amount of work.

To make it easier to understand how effort is reduced, I calculated two realistic changes in 1RM that could occur with heavy weight lifting.  Let's say that a cyclist needs to produce 50 pounds of pedal force to maintain a hard pace.  If the cyclist had a 1RM of 200 pounds, then it would take 25% of maximal effort to maintain that hard pace.  After spending time with heavy weight lifting, the cyclist improved the 1RM to 230 pounds.  Next time the cyclist tries to maintain that hard pace, it will feel easier because instead of using 25% of maximum, only 21.7 % is needed to maintain that pace.
  • Initial maximal strength:  1RM = 200 lbs / 1 repetition
    • Cycling requirement:  50 lbs / pedal stroke = 25.0% of maximum
  • Improved maximal strength:  1RM = 230 lbs / 1 repetition
    • Cycling requirement:  50 lbs / pedal stroke = 21.7% of maximum
Being able to operate at a lower percentage of maximum is a clear advantage that endurance athletes can take advantage of.  To reap the benefits of this method, a weight greater than 66% of 1RM must be used (3).  For the greatest possible improvement in strength, use 100% 1RM (2).  If you choose to lift 100 percent, please be smart and get a spotter!

2.  HIGH REPETITION TRAINING:  High repetition training or HRT involves three to four sets of lifting relatively light weights (30-50% 1RM) anywhere from 30 to 50 times.  This is a popular method for increasing muscular endurance because the training effects are more obvious and easier to understand.  High repetition training improves muscular endurance through four mechanisms different from the method above:
  1. HRT produces more lactate than the levels found in competition
  2. Improves the individual's tolerance to the fatiguing effects of lactate
  3. Promotes local circulation to the working muscle group(s)
  4. Enhances metabolism and other by products
Of the three mechanisms, one and two are the major reasons why it's important to implement this type of training to a program.  Greater tolerance to lactate is advantageous to anyone who needs to work at high intensities for a long time.  This will translate to better performance in competition and training.  I also wanted to mention that the load recommended for this type of training is very similar to the optimal load for maximal power training (approximately 30-45% 1RM) (2).  For the greatest improvement in power, studies have found that 30% of maximum will optimally improve power (5,6).  To specifically improve power-endurance, the repetitions may also be performed explosively.

Another variation of this method involves completing the greatest number of repetitions within a set time.  For example, a 5k runner will likely run 400 meters in 50 seconds repeatedly.  This variation might sound familiar because it is essentially "interval training."

3.  VARIABLE LOAD TRAINING:  This method combines the best of both worlds that heavy weight training and high repetition training can offer.  Because methods one and two produce similar improvements in muscular endurance, this type of training is an excellent way to reap both of the benefits (2).  To perform this type of training, a number of progressively lighter loads should be performed consecutively with little to no rest.  The first load(s) must be higher than 66% 1RM to improve maximal strength gains (3).  The final load(s) should be 30-50% 1RM to increase lactic acid production and improve tolerance to the effects of lactic acid.  Successfully lifting all of the loads marks the end of the first set.  See the sample program below.
  • 10 repetitions/ 80% 1RM
  • 12 repetitions/ 60% 1RM
  • 15 repetitions/ 40% 1RM
  • 10 repetitions/ 30% 1RM explosive

References:
  1. Anderson T. & Kearney J. (1982) Effects of three resistance training programmes on muscular strength and absolute and relative endurance.  Research Quarterly for Exercise and Sport 53, 1-7.
  2. Applied anatomy and biomechanics in sport. New York: Blackwell Scientific Publications, 1994. Print.
  3. McDonagh M. & Davies C. (1984) Adaptive response of mammalian skeletal muscle to exercise with high loads. European Journal of Applied Physiology 52, 139-155.
  4. Plowman, Sharon A., and Denise L. Smith. Exercise physiology for health, fitness, and performance. 3rd ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2011. Print.
  5. Kaneko M., Fuchimoto T., Toji H. & Suei K. (1983) Training effect of differing loads on the force-velocity relationship and mechanical power output in human muscle. Scandinavia Journal of Sport Science 5, 50-55
  6. Moritani T., Muro M., Ishida K. & Taguchi S. (1987) Electrophysiological analyses of the effects of muscle power training. Research Journal of Physical Education in Japan 1, 23-32.
  7. Schmidtbleicher D. & Haralambie G. (1981) Changees in contractile properties of muscle after strength training in man. European Journal of Applied Physiology 46, 221-229.