Exercise is Medicine

by Jade Teta ND, CSCS, and Keoni Teta, ND, LAc, CSCS

Lower-Body Training for Full Body Results?

Given the risks of frailty and the benefits of both strength and lean body mass, it is useful for clinicians to have tools that affect these areas. Focused weight lifting, especially using the legs, is a potent reservoir of hormonal potential and metabolic signaling. In fitness and body-building circles, this belief is encapsulated by the mantra “train the legs if you want to grow your arms.”

There have been countless exercise protocols built around this idea. As physicians, we have used these protocols on ourselves and with our patients with good clinical outcomes. But does any objective research support this contention? Can leg training really enhance training adaptations in other parts of the body?

Local Effects Are Most Important

There is little question that local effects of weight training are most important to adaptation. In other words, if you want muscular arms, it goes without saying that you must train the arms. Leg training is certainly not required to increase strength and hypertrophy in the arms, but the question is, can it help?

The theory behind using the legs to enhance whole-body muscle growth has to do with the transient hormonal response caused by resistance training. Testosterone, both endogenous and exogenous, has been shown to play a strong and perhaps required role in muscle growth.^1–4,18 The impact of human growth hormone (HGH) and its role is more controversial, with most agreeing it at best plays a supportive role.^5,6 And then, of course, there are the myokines and their now documented role in mechanisms of muscle gain.¹⁶

The Studies

The first study that we reviewed regarding this theory was published in 2001 by Hensen et al⁾.⁷ Sixteen untrained young male subjects were randomized to an arm training only group (A) and an arm plus leg training group (LA). The A group trained one arm only with the other arm acting as a control. The LA group trained legs first and then followed up immediately with arm training in the same manner as (A). The exercise protocols consisted of 8 sets for the arms and legs using an 8–12 rep max on bicep curl and leg press respectively. Training was carried out twice a week for 9 weeks.

The results of this study showed a direct correlation between hormonal elevations induced by training (namely testosterone) and isometric strength gains. The gains in strength were 37% and 10% in the LA group’s trained arm and control arm respectively. The numbers for the A group were 9% and 2% improvement.

This study does have potential flaws. It is now understood there is a significant interindividual difference as it pertains to weight training effects on hypertrophy, strength gains and hormones.^8–10 In addition, this study was not able to match the LA and A groups on initial arm strength, showing a much weaker arm strength on average for the LA group leaving the potential for much greater gains.

West et al. used a similar exercise protocol as the Hensen study except legs were done after arm exercise instead of before.¹¹ This study involved 12 young men training over a period of 15 weeks. The participants acted as their own controls, training each arm independently under different conditions. A significant strength of this study over the Hensen et al. paper. The low hormone condition (LH) involved training one arm without leg training. The high hormone condition (HH) involved training the other arm followed by leg training. While the HH group did enjoy significantly greater hormonal responses, there was no difference in arm muscle hypertrophy or strength between groups after 15 weeks.

One confounding variable for the West research was the use of a pre- and postrecovery protein shakes in the protocol. Fed state exercise along with training and postexercise recovery feeding is known to create a more potent anabolic environment.¹⁹ Insulin was shown to be significantly elevated in subjects throughout the training periods. This “insulin effect” should not be taken lightly. Insulin is a powerful anabolic stimulus and may have “washed out” any acute anabolic effects of the other hormones.

The most recent study on this topic that we could find again used a similar design to the West study above but with out the fed-state protocol. This time the leg training preceded the arm training.¹² Nine young males trained over 11 weeks doing 2 sessions with one arm trained alone (A) and 2 sessions with the other arm trained immediately after leg training (LA). Muscle hypertrophy and 1 rep max strength improved significantly in the arms of the LA group versus the A group.

Finally, the most interesting study on this topic, from our point of view, comes from Haruhiko et al.¹⁵ The West et al. group maintains that hormonal elevations, despite being larger then resting levels transiently in response to leg training, do not reach levels high enough (such as when under the use of exogenous sources) to have much impact on muscle hypertrophy and have shown that they may not be implicated in muscle growth at all.²⁰ Yet, many of their protocols were carried out in the fed state. Nevertheless, this has led many to question the validity of hormones’ having any true meaningful impact on muscle growth rightly leading them to be skeptical of any cross over effects such as espoused by the “train legs then arms method.”

However, high-intensity exercise is known to elicit a much wider array of signaling molecules than simply HGH and testosterone. These other “hormonelike molecules” include IL-6, IL-15, IL-8, lactate, and nitric oxide.¹⁶ These local metabolites may be playing a greater role in the favorable adaptations seen anecdotally and noted in some of the studies above. Indeed, several studies on vascular occlusion training show greatly elevated muscle-signaling responses locally and systemically as well as improved muscle growth when compared to traditional training.^13,14,17

Haruhiko et al. had 15 untrained young men exercise for 10 weeks.¹⁵ They trained twice weekly using a similar design to the studies above. One arm was trained without any leg involvement (A), while the other arm was trained before a light leg workout with the legs under vascular compression (LA+O). This vascular occlusion technique was shown to significantly elevate noradrenaline over the arm only group, but HGH and testosterone were not different between groups. The LA+O enjoyed a significant muscle growth and strength gain advantage compared with the A group.

Final Thoughts

The idea that there are anabolic crossover effects from training one set of muscles (i.e., the legs) to another (i.e., the arms) is a controversial topic. The studies above give us mixed messages. The order or intensity of training may be important here. Both studies using a legs-first approach showed impact. This strategy would both elevate the intensity of the workout generating greater hormonal response, and allow arm training to coincide with the largest peaks in hormonal activity induced by leg training.

Also, the vascular occlusion study, which used light leg training and showed no HGH and testosterone advantage to leg training, hints that the transient elevations in traditional anabolic hormones may be far less important than other signaling factors such as IL-6, IL-15, and other myokines. This may explain why low intensity, vascular occluded leg training showed an effect.

Obviously, the feeding effect cannot be ignored. Insulin is a far greater anabolic stimulus than either HGH or testosterone. Proper eating strategies in and around muscle building protocols are likely the most important consideration coming out of this review. Our guess would be the impact of insulin supersedes any positive benefits from the “train legs to build arms” approach.

Of course, the real answer is that we don’t yet know. While the studies reviewed here suggest that this method is viable, they also leave us with several unanswered questions as to the mechanism. More research should be done, but for clinicians in the field looking to maximize lean body mass for the whole body, our clinical experience says, when other approaches are not working, train the legs first.

Notes

1. Kraemer et al. Hormonal responses and adaptations to resistance exercise and training. Sports Medicine. 2005;35:339–361.

2. Bhasin S, Woodhouse L, Storer TW. Proof of the effect of testosterone on skeletal muscle. Journal of Endocrinol. 2001;170:27–38.

3. Inoue et al. Androgen receptor antagonist suppresses exercise-induced hypertrophy of skeletal muscle. European Journal of Applied Physiology and Occupational Physiology. 1994;69:88–91.

4. Kvorning et al. Suppression of endogenous testosterone production attenuates the response to strength training: a randomized, placebo-controlled, and blinded intervention study. American Journal of Physiology, Endocrinology and Metabolism. 2006;291:E1325–E1332.

5. Rennie MJ. Claims for the anabolic effects of growth hormone: a case of the emperor’s new clothes? British Journal of Sports Medicine 2003;37:100–5

6. McCall et al. Acute and chronic hormonal responses to resistance training designed to promote muscle hypertrophy. Canadian Journal of Applied Physiology. 1999;24:96–107.

7. Hansen et al. The effect of short-term strength training on human skeletal muscle: the importance of physiologically elevated hormone levels. Scandinavian Journal of Medicine and Science in Sports. 2001;1: 347–354.

8. Beaven et al. Salivary testosterone and cortisol responses in professional rugby players after four resistance exercise protocols. Journal of Strength & Conditioning Research. 2008;22(2):426-432.

9. Beaven et al Significant strength gains observed in rugby players after specific resistance exercise protocols based on individual salivary testosterone responses. Journal of Strength & Conditioning Research. 2008;22(2):419-425.

10. Hubal et al. Variability in muscle size and strength gain after unilateral resistance training. Medicine and Science Sports Exercise. 2005;37: 964–972.

11. West et al. Elevations in ostensibly anabolic hormones with resistance exercise enhance neither training-induced muscle hypertrophy nor strength of the elbow flexors. Journal of Applied Physiology. 2010;108(1):60-67.

12. Rønnestad et al. Physiological elevation of endogenous hormones results in superior strength training adaptation. European Journal of Applied Physiology. 2011;111(9):2249-2259.

13. Takarada et al. Rapid increase in plasma growth hormone after low-intensity resistance exercise with vascular occlusion. Journal of Applied Physiology. 2000;88:61–5.

14. Reeves et al. Comparison of hormone responses following light resistance exercise with partial vascular occlusion and moderately difficult resistance exercise without occlusion. Journal of Applied Physiology. 2006;101:1616–22.

15. Haruhiko et al. Cross Transfer Effects of Resistance Training with blood flow restriction. Medicine and Science in Sports and Exercise. 2008;40(2):258-263.

16. Teta, J and Teta K. Exercise is Medicine: The Anti-inflammatory Effects of High Intensity Exercise. Townsend Letter. November 2006.

17. Teta, J and Teta K. Exercise is Medicine: Vascular Occlusion Training For Muscle Growth. Townsend Letter. February/March 2011.

18. Vingren et al. Testosterone physiology in resistance exercise and training: the up-stream regulatory elements. Sports Medicine. 2010;40:1037–1053.

19. Van Loon et al. Ingestion of protein hydrolysate and amino acid carbohydrate mixtures increases postexercise plasma insulin responses in men. Journal Nutrition. 2000;130(10):2508-2513.

20. West et al. Anabolic processes in human skeletal muscle: restoring the identities of growth hormone and testosterone. The Physician and Sportsmedicine. 2010;38(3):97-104.