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10/1/2023 Newsletter

Aragon AA, Tipton KD, Schoenfeld BJ. Age-related muscle anabolic resistance: inevitable or preventable? Nutr Rev. 2022 Aug 26:nuac062. doi: 10.1093/nutrit/nuac062. Epub ahead of print. PMID: 36018750.


Frailty and Sarcopenia among those who are aging are some of the biggest health threats. We all likely now have other goals and reasons for pursuing fitness, so we forget about many of the health benefits.


Sarcopenia is the loss of muscle that is associated with age and inactivity, this has been labeled as a disease state as this significantly impacts someone's health, quality of life and robustness. Typically muscle mass peaks in our 30’s- 40’s but has been observed to have a larger variability in those with high levels of training.


About 10% of those over the age of 60 in the general population have sarcopenia. Those who are in nursing homes have a rate of 31-51% depending on their sex. Part of the contribution to this is our general decrease in response to protein as we age, and decline in response due to inactivity. It also appears that systemic inflammation, and insulin resistance (like that seen with diabetes) play a role here.


Also, it may not be just age that is associated with these changes. As often as we age we become more sedentary, more likely to become obese, and have other factors that decrease muscle protein synthesis. Obesities, itself seems to be a large factor in this due to the chronic inflammation associated with this. But this can be exacerbated by lifestyle, such as minimal activity, and food choices.


Some studies suggest that desirable body fat percentages for health are 12-20% in men and 20-30% in women. But is hard to accurately measure while we are alive to have exact percentages.


But in those who are likely to have anabolic resistance, or that we would be concerned with developing this it is important to note that multiple approaches work better to combat this. For example, increasing overall protein intake, and quality of protein does not appear to be enough if a stimulus is not provided to increase the need for protein utilization. In these clinical populations it appears that walking in some cases can be enough. But consistent resistance training appears to blunt this response the most, paired with sufficient protein intake, dispersed throughout the day. And it appears that maintaining strength and getting stronger over time also appears to be a good way to maintain function, and maximize health outcomes related to resistance training. It also appears that its “never too late” to start because movement and exercise can help at any age.


Protein recommendations are usually between 1 g/kg-1.2 g/kg in healthy adults and is suggested to be 1.2-1.5 g/kg in those more likely to be malnourished. But to maximize hypertrophy and muscle function we see numbers more like 1.6-2.2 g/kg. And because my math skills aren't so good anymore its easier if you convert your bodyweight to KG and use these ranges rather than me provide ranges in g/lb.


It seems that meals of around 25-30 grams of protein per meal which contain at 2.5-2.8 g of leucine cause peak activation of pathways that support muscle growth. This doe not mean that you cannot have more, it just means that this amount is what opens the doorway for nutrients to have the maximal effect. And it appears that doses of .4-.6g/kg is the upper limit per dose. So for me who is 93 kg that is 37-56g of protein at a meal. And to maximize this effect as this pathway remains highly active and cannot be overcome again for 3-5 hours it is practically recommended to have 3-4 meals per day to maximize the effects from dietary protein on muscle growth (protein has other benefits as well such as satiety).


Typical diets skew protein intake towards singular meals in the general population as well, which is why in some instances it is beneficial to have people start distributing this across meals. Additionally, it appears that without physical activity the effect of this is much less.


Some supplements play a role in this population as well, as when not intaking enough protein or getting enough creatine from dietary sources supplementation is extremely beneficial. As well as when deficient in vitamin D (200-1000 IU per day), and HMB can be beneficial, again largely when deficient or in malnourished individuals.


Overall, age related anabolic resistance is a multifaceted issue but this article should provide some recommendations likely to help.


Handford MJ, Bright TE, Mundy P, Lake J, Theis N, Hughes JD. The Need for Eccentric Speed: A Narrative Review of the Effects of Accelerated Eccentric Actions During Resistance-Based Training. Sports Med. 2022 Sep;52(9):2061-2083. doi: 10.1007/s40279-022-01686-z. Epub 2022 May 10. PMID: 35536450.


Typically, the eccentric portion of exercises are done in a slow and very controlled manner, and most people would say that they need to be a longer duration to maximize hypertrophy. During the eccentric phase (lowering portion) can usually perform 20-60% more than our concentric (raising) 1 rep max. And during this phase the tension or force on a muscle can be much higher, especially at higher velocities. This is because as the velocity increases we need more force to slow down the weight to come to a stop.


When eccentric actions are performed maximally we also see larger recruitment of motor units. And this seems to be the case across muscle fiber types. Further, slower eccentrics tend to lead to less force output and volume tolerance during concentric phases, thus if volume is not matched, would reduce session volume. Which is not desirable as overtime we are striving to increase the amount of volume we can perform to help produce hypertrophy and strength gains. Short eccentrics under 2 seconds seem to support faster velocities and greater power as well. But still needs to be studied long term.


Prior reviews showed in general that there is no significant difference in hypertrophy when a repetition takes .8 seconds or 8 seconds, and recommended eccentrics should be 2-4 seconds. In this review they theorize that due to the increase in volume and muscular tension seen when eccentrics are 2 seconds or less that it would make more sense to perform this practically, however more research is needed.


Practically we can also potentially see more growth when the eccentric portion is accelerated as well using things like bands. However this is typically performed with the band being released at the bottom to then allow for maximal concentric velocity. So this is only most practical with plyometrics or for single rep movements, due to the need to reset the band or device after each rep.


Practically there seems to be little difference between <2 second eccentrics and those that take up to 6 seconds. However practically we may apply these in various ways. Especially in a rehab setting providing tempos is a good way to reduce the load to make training more tolerable due to pain. Further, there are cases where if someone has poor mind muscle connection having longer reps/sets may help with learning to feel the muscle trying to be stimulated.


Its likely more research is needed long term to provide an appreciable difference and accounting for many factors that most trained individuals will have questions about.


Reya M, Škarabot J, Cvetičanin B, Šarabon N. Factors Underlying Bench Press Performance in Elite Competitive Powerlifters. J Strength Cond Res. 2021 Aug 1;35(8):2179-2186. doi: 10.1519/JSC.0000000000003097. PMID: 30908368.


Prior studies have suggested that muscle mass and bench press 1RM are related to this study, so this study wanted to further investigate what factors in powerlifters related to bench press performance. EMG work has also suggested that the pec major, tricep, anterior deltoid, and lat contribute the most to bench press performance. And that more advanced lifters have more variation in lifting than novice lifters suggesting they have adopted more individualized strategies that work best for their performance.


The lifters they looked at were between the ages of 18-26 with one who was 53, and had a bench press performance in competition contributing to 90 wilks points.


They found the most relationship between structural factors, measures of lean body mass, bone mass, and upper arm circumference with performance. While technical measures like arch height, and force output between a lifters feet and the floor related less to performance. And obviously, the activity of elbow extension and horizontal adduction had large impacts on bench performance, but also shoulder flexion strength.


The authors surmised that about 59% of bench performance was related to neuromuscular factors, lean body mass, and anthropometrics. So it seems that potentially accumulating more body mass within the limitations of a weight class has positive effects on bench performance. According to the EMG measurements they took during the study the muscles most active in order were: triceps, anterior deltoid, pec major, and Lat.


So bad news if you have a long upper arm, it will likely negatively effect your bench press numbers. However, interpretations of this study should be made with caution due to lower sample size and other limitations, as the authors made note of in the study.


Sato S, Yoshida R, Kiyono R, Yahata K, Yasaka K, Nunes JP, Nosaka K, Nakamura M. Elbow Joint Angles in Elbow Flexor Unilateral Resistance Exercise Training Determine Its Effects on Muscle Strength and Thickness of Trained and Non-trained Arms. Front Physiol. 2021 Sep 16;12:734509. doi: 10.3389/fphys.2021.734509. PMID: 34616309; PMCID: PMC8489980.


As many are aware it has been discussed more and more how range of motion impacts muscular adaptation, namely growth. In general, there is a trend where full range of motion training results in more growth, than partial range of motion, with a large body of evidence in the legs. Also full ROM training appears to also aid strength more than partial range of motion training, in general but there is nuance to that conversation beyond the scope of this review.


Further, there has been more new evidence showing that the range of motion per se may not be the most important factor but the length that a muscle is taken to or trained in that impacts growth and strength. As some research has shown even partial range of motion training but done with a muscle at a lengthened position seems to elicit the same effects as full range training. It is important to note for the review of this study that there is this phenomenon called the cross over effect. This effect is where you can train one limb, and due to how our nervous system works and adapts we can see strength improvements on the opposite side without training it. This study also looked at the effect of this phenomenon.


Its also important to note that the participants of this study were untrained, male and female around the age of 20. The training protocol involved one group doing a preacher style curl with a dumbbell, and the other group performing a similar movement but with their bicep at a longer muscle length (0-50 degrees of shoulder extension), a third group did no training. The training ramped up from 30% to 50% up to 100% by the end of the protocol, using 3 sets of 10 with 3 minutes rest and 2 second eccentric portions, and they performed a total of 10 training sessions.


The authors findings were that the group that performed the bicep curl in an extended shoulder position increased their strength more, and hypertrophy, more than the group who did preacher style curls. The difference was 2.6x more for muscular growth, in the extended position group than the preacher curl group. Also a significant cross over effect was only noted in those training in the extended position as well. Further, the muscular growth appeared to be more in the distal portion of the muscle versus the end closer to the shoulder.

This may be related to that the stretch produced in the extended position results in more tension on the muscle impacting activation and metabolic demands. This style of training may also place more demand on the central nervous system adaptations.


While promising and adding more value to the idea of training at long muscle lengths, we need to consider this was done in young individuals, without training history, and was a small sample size, and only over 5 weeks.


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