USAWA

AGING AND STRONG

Part IV: Still Ageless

By Dan Wagman, Ph.D., C.S.C.S.

 I’ve really enjoyed revealing the science behind the effects of aging (click here for Part I, Part II, and Part III). I derive at new-found levels of motivation knowing that my age won’t impact my strength until I’m close to 70. I sincerely hope that the readers of this series will feel similarly. Though you cannot argue the scientific facts, they do seem to fly in the face of what just about every older lifter has experienced. It is, therefore, necessary to look even deeper into the impact age might have on your muscles’ ability to handle a loaded barbell.

 Older and Pumped

In 1945 a Captain in the United States Army Medical Corps investigated the effects of lifting weights on injured soldiers.(1) His research highlighted many important lifting insights, among them that regardless of how old an injury might be, or how old the soldier might be, if he began a weight training protocol and over time increased the weight lifted, he would be able to make sizable gains. Still, as research built upon these findings, sport scientists began to understand that as a person ages the degree of muscle mass decreases. But since lifting weights via a carefully designed training approach increases muscle mass, could it turn old muscles young?

Researchers at the Department of Medicine and Physiology at Rochester University, NY, recruited young (22 to 31) and older (62 to 72) males and females.(9) Baseline MRI studies for muscle mass were conducted, then 3-RM baseline strength was recorded. At baseline there were no significant differences between age groups in the size of the biceps and hamstrings, but the quads in the older group were 22% smaller. Also, at the beginning of the study the older group was significantly weaker than the younger group. Next, the subjects began a three-month scientific strength training program for the quads, hamstrings, lats, and biceps.

Upon completion of the training regimen the researchers found increases in bicep and hamstring size were significantly less in the older group (13% and 7% difference, respectively). For the quads, however, there were no significant differences between groups. In terms of the amount of strength the subjects developed, there were no differences between groups. As an example, overall the biceps increased in strength for the young group by 21% and for the older group by 19%. When, however, the scientists considered how much weaker the old group was at baseline, biceps strength increased in the older group by 64% compared to 28% for the younger group. The research team concluded that, in terms of gains in muscle mass, “…the effect of age on responses to exercise in one muscle group cannot be generalized to all muscle groups.” And related to strength gains they stated, “…substantial strength gains can be achieved in older subjects even in the absence of muscle hypertrophy [growth].”

A few years later an international group of scientists from Finland, Australia, and the United States collaborated in a much more extensive study.(3) They recruited young (29 ±5 years) and older (61 ±4 years) men to examine the effects of an involved and highly scientific 10-week training program on their muscle mass, peak strength, and explosive strength. They performed the squat, leg extension, leg curl, calf raise, back extension, bench press, and crunch. Each week had training days dedicated to muscle growth, muscle strength, or muscle power. At the end of this project both groups recorded significant gains in all measures, though the physiological means by which they were achieved were a bit different.

What appears to be the case is that older people can make the same amount of strength gain compared to a younger person, but there are differences in how their bodies respond and adapt to weight training. One study actually found that after a 6-week weight training period the maximal motor unit (a motor unit consists of the nerve and all of the muscle fibers it innervates) discharge rates increased in young subjects by 15% compared to 49% for older subjects.(5) This is an indication that as you age, there might be a shift away from increasing muscle mass to increasing neurological function as the main driver for strength gain.

From Nerves to Protein

To expand upon this interesting finding a 2014 study looked at what differences there might be between men with average ages of 29 and 64 years.(8) The subjects participated in a 10-week high-volume medium-load training program designed to enhance muscle growth. Although the subjects performed whole-body training the research emphasis was on the leg press, leg extension, and leg curl. The researchers found that despite the fact that both groups made “large increases in strength” (13% young, 14% old), “the dominant mechanisms that may have led to these increases appear to be different between the two groups.” This, because although strength increases were large, they were accompanied with a significant increase in muscle mass in the younger participants, which was not found in the older ones.

The research team acknowledged that the issue of diet was not addressed in their study and believed that it’s possible that the older individuals’ dietary intake may have resulted in less gains in muscle mass. Previous work found that following a 21-week weight training protocol the younger trainees made quicker gains in strength early on compared to the older ones. At the end of the training cycle, however, strength gains were equal.(7) The gains in muscle mass, on the other hand, were greater in the young group and since the subjects’ diet was recorded, the scientists were able to link smaller gains in muscle mass in the older subjects to less daily energy and protein intake.

So protein remains a critical aspect when it comes to developing muscle mass, regardless of age. But since a muscle’s protein “accretion,” as physiologists like to put it, is a highly complex matter related to hormones, cell signaling, etc., it could be that these mechanisms are stunted in older lifters. Scientists from the Universities of Alabama and Arkansas found out, however, that if you trained young and old subjects with weights over a 16-week period, there is “no evidence” that older subjects would synthesize protein to a lesser extent than younger ones.(6) So regardless of age, all you have to do is make sure you pump iron and ingest sufficient amounts of protein. In the short term, if you’re older and say, you’re supplementing your diet with essential amino acids, all you need to know is that your protein synthesis rates are a bit slower compared to younger people (3-6 hrs. vs. 1-3 hrs., respectively). In the long term, however, there are no significant differences.(2)

The Middle-Aged

As you can see, the vast majority of studies tend to look at strength and age between young people in their 20’s and older people in their 60’s and beyond. But since all-round weightlifting considers people to be Masters at 40 and starts to apply an age adjustment, it would be important to know what difference there might be between 40-year olds and 70-year olds. An international group of researchers recruited healthy and fit subjects active in walking, jogging, cross-country skiing, aerobics, and cycling—though none had background in strength training—representing both genders and at average ages of 40 and 70.(4) The subjects trained with weights for six months with the goal of enhancing maximal and explosive strength via a periodized training regimen, meaning that training intensity and volume were manipulated over time to maximize physiological adaptations. Once the scientists crunched the numbers, here’s what they found:

• All subjects increased their muscle mass significantly (4.9% men 40, 9.7% women 40, 5.8% women 70), except for 70-year old men (2.1%);
• large increases in maximal isometric leg extension strength were recorded: men 40 and 70 by 36%, women 40 by 66%, and women 70 by 57%;
• maximal isometric leg curl strength increased significantly by 14% in both groups of men and by 22% in women 40 and 17% in women 70;
• the rate at which subjects could reach maximal strength increased significantly: men 40 41%, men 70 40%, women 40 31%, and women 70 28%;
• all groups also increased the electrical activity of the muscles investigated significantly;
• maximal leg extension strength increased significantly in all groups: men 40 22%, men 70 21%, women 40 34%, women 70 30%;
• the squat jump was used to measure improvements in lower body explosiveness with all groups recording significant increases, though the increases achieved by the 70-year olds reached its peak after two months of training whereas for the 40-year olds it was after four months of training; men 40 11%, men 70 24%, women 40 14%, women 70 18%.

The main finding of this extensive study reveals that healthy and fit 40- and 70-year olds can make tremendous gains in strength and power. And what struck the scientists was that these gains were much greater than what the smaller, yet still significant, gains in muscle size would suggest.

What these studies teach us is that if you lift weights and you’re older, the age factor seems to have little impact. What does seem to occur, however, is that in older people the way in which the body responds to strength training is a bit different. Moreover, it appears that certain exercises and body parts are impacted differently, meaning that whatever age effect there may be, it doesn’t impact the entire body equally. But before we conclude this series, there’s one more issue to consider—recovery. A common mantra of older lifters is that they just can’t recover from training the way they used to. We’ll take a close look in Part V.

References

1. Delorme, T. Restoration of muscle power by heavy-resistance exercises. The Journal of Bone and Joint Surgery. 27:645-667, 1945.
2. Drummond, M., et al. Skeletal muscle protein anabolic response to resistance exercise and essential amino acids is delayed with aging. Journal of Applied Physiology 104:1452-1461, 2008.
3. Häkkinen, K., et al. Changes in agonist-antagonist EMG, muscle CSA, and force during strength training in middle-aged and older people. Journal of Applied Physiology 84(4):1341–1349, 1998.
4. Häkkinen, K., et al. Changes in muscle morphology, electromyographic activity, and force production characteristics during progressive strength training in young and older men. Journal of Gerontology: Biological Sciences 53A(6), B415-B423,
5. Kamen, G. and C. Knight. Training-related adaptations in motor unit discharge rate in young and older adults. Journal of Gerontology: Medical Sciences 59A(2):1334-1338, 2004.
6. Mayhew, D., et al. Translational signaling responses preceding resistance training-mediated myofiber hypertrophy in young and old humans. Journal of Applied Physiology 107:1655-1662, 2009.
7. Mero, A., et al. Resistance training induced increase in muscle fiber size in young and older men. European Journal of Applied Physiology 113:641-650, 2013.
8. Walker, S. and K. Häkkinen. Similar increases in strength after short-term resistance training due to different neuromuscular adaptations in young and older men. Journal of Strength and Conditioning Research 28(11):3041–3048, 2014.
9. 9.Welle, S., et al. Effect of age on muscle hypertrophy induced by resistance training. The Journals of