Exercise professionals involved with older adults pay a great deal of attention to the lower limb prime movers¹ and exercises² which will enhance the strength and power of these important muscles, and so we should. There are all sorts of ingenious ways to increase the strength, function and aesthetics of these muscles, just take a quick look at Instagram and you’ll see what I mean. The hip abductors are now recognised also, in both research and practice, as playing a pivotal role in hip and knee function influencing gait and postural stability, particularly in the medio-lateral plane. But what about the hip adductors? Are they a forgotten piece of the puzzle? Rarely do we see much attention paid to exercising these muscles of older adults in any sort of meaningful way³. This is interesting in and of itself and a curiosity, but the inference is that the adductor muscle group is not viewed as important enough to dedicate any time to specifically develop its neuromuscular capacity irrespective of some recent research that certainly suggests otherwise. There is now enough evidence to support the adductors being treated as a distinct target for improved muscle strength and power production. In fact, FGS would contend that this muscle group deserves the same degree of focus as the quads, GMax, hamstrings and hip abductors in any resistance training program for older adults given the following:
The adductor magnus (AM), the 3rd largest muscle can be considered as a primary antigravity muscle, like the GMax (Takizawa et al 2018).
Age-related hip adductor strength loss appears to be more pronounced compared to the knee extensors (Daun & Kibele, 2019).
Postural instability with ageing is especially problematic in the medio-lateral plane (Mille et al 2013).
Neuromuscular rate of activation of adductors (AM) is significantly lower in older versus younger adults for both forceful static muscular contractions (IMVC) and dynamic recovery following lateral balance perturbations (Inacio et al 2019).
Power-based resistance training of the hip adductors (and hip abductors) has been shown to elicit improvements in maximal neuromuscular performance and enhanced medio-lateral balance recovery. Traditional (slower tempo) performed resistance training did not result in significant improvements in isolated or balance-related neuromuscular or biomechanical performance (Inacio et al 2018).
Based on the abovementioned research, FitGreyStrong’s recommendation is to ensure that weight-bearing exercises that load and challenge the adductor muscle group (frontal plane) be included in resistance training programs of older adults. Moreover, it should be acknowledged that open kinetic chain seated machinesmay not provide the appropriate neuromuscular challenge to bring about improvements in medio-lateral balance and function (Daun & Kibele, 2019; Inacio et al 2018) however, further research is required4.
Footnotes:
1 Quads, GMax and hamstrings
2 Squats, deadlifts, glute bridges, hip thrusts, leg curls, sit-to-stands, step-ups etc
3 The same could be said for the hip flexors where age-related muscle mass and strength losses occur disproportionately compared to other major muscle groups and this obviously impairs physical function and gait potentially increasing the risk for falls.
4 Thanks to Rhys Manchester for pointing out some inconsistencies with these concluding remarks.
For local Townsville residents interested in FitGreyStrong’s specialised Exercise Physiology services or exercise programs for older adults or for Master’s competitors wanting to enhance athletic performance, contact FitGreyStrong@outlook.com or phone 0499 846 955 for a confidential discussion.
For other Australian residents or oversees readers interested in our services, please see here.
Disclaimer: All contents of the FitGreyStrong website/blog are provided for information and education purposes only. Those interested in making changes to their exercise, lifestyle, dietary, supplement or medication regimens should consult a relevantly qualified and competent health care professional. Those who decide to apply or implement any of the information, advice, and/or recommendations on this website do so knowingly and at their own risk. The owner and any contributors to this site accept no responsibility or liability whatsoever for any harm caused, real or imagined, from the use or distribution of information found at FitGreyStrong. Please leave this site immediately if you, the reader, find any of these conditions not acceptable.
In a recent meta-analysis (see here), vitamin D was found to provide an additive benefit for older adults partaking in resistance training (RT). In other words, when compared to older adults taking a placebo, significantly greater gains in muscle strength were achieved in those supplemented with vitamin D. However, upon closer analysis several issues become obvious that are difficult to reconcile. The following discusses some of these issues inherent in the findings of this paper (see below).
The group 1 analysis of 3 trials finds vit D supplementation augments muscle strength of the lower limbs, SMD=0.98; see fig 2 below. (Please click on any image to open and make larger for viewing).
…but what is with the scale used for the x-axis; it seems all wrong…..all the green squares sit nicely on zero……. and where is my forest plot with 95% CI bars and my black triangle to show overall SMD?
As a crude comparison & to put this in context, Chilibeck et al (2017) found SMD=0.25 for the effect of creatine supplementation on lower body strength during RT in older adults. Perhaps the most effective supplement available? Could vit D really be that much better?
The authors acknowledge serious inconsistency with substantial heterogeneity (see table 5) for this outcome measure and even suggest that maybe: “….these studies were unsuitable for comparison”, but conclude nonetheless that there is: “tentative support for the additive effects of RT and vit D supplementation for the improvement of muscle strength in older adults”, including those replete in Vit D.
The Uusi-Rasi et al (2015) trial was weighted heavily (75%) and rightly so being the most well designed, largest & longest RCT to date. In fact SMD of this trial in the group 1 analysis = 1.16. This is very impressive and clinically relevant if accurate and valid. Uusi-Rasi et al (2015) in contrast states: “Irrespective of vit D, exercise increased muscle strength. The predicted mean increase in lower limb extension strength was almost 15% in both exercised groups and differed significantly from the placebo without exercise group.”
“Another unexpected finding was that exercisers treated with vit D supplementation showed consistently smaller benefits than exercisers receiving placebo……our results indicate that vit D may not improve neuromuscular function, at least when vit D intake is sufficient.” The largest and longest RCT to date found no additional – and perhaps even attenuated – benefit of vit D supplementation in replete resistance-training older adults, which is at complete odds to the meta-analysis.
The Agergaard et al (2015) trial showed no additional benefit of vit D on muscle strength in older adults (vit D replete). Sample size for older adults was very small also and weighted acccordingly in the meta.
….and Bunout et al (2006) found that combined calcium/vit D supplementation was no more effective than calcium-only supplementation in older adults undergoing RT but – and this is a critical point of difference to the other 2 studies.
– all participants were arguably vit D insufficient; to be included participants had to be 16 ng/ml (40 nmol/L) or less for serum 25(OH)D. An important point that was missed by the authors of the meta-analysis (see further below).
These 3 studies included in the group 1 analysis of muscle strength of the lower limbs were identified as “all participants took part in RT and the intervention arm was supplemented with vit D (describing the additive effect of vit D supplementation when combined with RT)”
However, Bunout et al (2006) did not include a RT group that received a ‘true’ placebo. Both exercising groups in this trial received supplementation of some sort.
….one group was supplemented with vit D & calcium (intervention), the other exercising group were supplemented with calcium-only (control). “……vit D was given along with calcium in this trial, since a low calcium intake can limit the effects of the vitamin.
To isolate the effect of the vitamin, controls for supplementation received calcium also.” However results showed there were no statistically significant differences between these groups in baseline to final percentage change for right and left quadriceps strength, and right and left hand grip strength. In fact, the RT plus calcium-only group achieved better mean numerical responses in strength (non-significant) when compared to the RT plus vit D/calcium group (see table 2)……..so is it somewhat unusual that such a large SMD was found in the meta favouring the group that received vit D?
The authors state in the meta discussion that: “Interestingly, although the studies included within group 1 did not specify serum 25(OH)D levels as inclusion/exclusion critieria, baseline and postintervention serum 25(OH)D were within the ‘sufficient’ range (>30 nmol/L).”
Now there are 2 issues with this statement. Firstly, it is false that all studies included in group 1 did not specify serum 25(OH)D levels as inclusion/exclusion criteria. Bunout et al (2006) in fact did just that and specified a cut-off point for inclusion.
Subjects were screened and included only if their serum 25(OH)D levels were 16 ng/ml (40 nmol/L) or less. Secondly, mean baseline serum 25(OH)D of the vit D supplemented group in Bunout et al (2006) was 12.4 ng/ml (30 nmol/L) and many experts would propose that serum 25(OH)D of around 30 nmol/L in older adults is insufficient. It is also worth noting that Vit D status for participants of each of the 3 studies varied considerable and could possibly confound the meta.
After reviewing the 3 trials very carefully (used in the group 1 analysis of Antonia and Greig 2017), the finding that vit D supplementation significantly augments muscular strength of older adults doing RT, including those replete for vit D (SMD=0.98), is perplexing.
It is plausible and there is some evidence that vit D supplementation may augment strength of exercising older adults that have insuffient or deficient levels of vit D [serum 25(OH)D <50 nmol/L & <25 nmol/L] but such data is as yet not forthcoming in older adults performing RT
After reviewing Antoniak & Greig (2017) in which vit D supplementation significantly enhances strength in older adults doing RT, I cannot but view the findings as an artefact possibly generated by the unresolvable and substantial heterogeneity that was detected in the analysis.
The conclusion of tentative support for the ergogenity of vit D in older RT adults, irrespective of serum 25(OH)D status, is therefore premature and unsubstantiated.
For local Townsville residents interested in FitGreyStrong’s Exercise Physiology services or exercise programs designed to improve muscular strength, physical function (how you move around during the day) and quality of life or programs to enhance athletic performance, contact FitGreyStrong@outlook.com or phone 0499 846 955 for a confidential discussion.
For other Australian residents or oversees readers interested in our services, please see here.
Disclaimer: All contents of the FitGreyStrong website/blog are provided for information and education purposes only. Those interested in making changes to their exercise, lifestyle, dietary, supplement or medication regimens should consult a relevantly qualified and competent health care professional. Those who decide to apply or implement any of the information, advice, and/or recommendations on this website do so knowingly and at their own risk. The owner and any contributors to this site accept no responsibility or liability whatsoever for any harm caused, real or imagined, from the use or distribution of information found at FitGreyStrong. Please leave this site immediately if you, the reader, find any of these conditions not acceptable.
Please note: This is a recurring subscription service which will be billed every 4 weeks.
If your goal is to improve your basic health and fitness, or build incredible strength and power, or enhance your overall athletic performance, or you simply want to get ‘buffed’ look no further. Personalised Programming with Mr FGS will design and deliver super effective regular monthly programs specifically tailored for YOU. Every 4 weeks customised workouts are delivered to help you reach your specific goals.
COST:
Please contact FitGreyStrong to discuss the fees regarding Personalised Programming.
You may cancel at anytime and all cancellations must be completed prior to your next billing date.
Please direct any questions to fitgreystrong@outlook.comfor further information.
DISCLAIMER:
All contents of the FitGreyStrong website/blog are provided for information and education purposes only and the Personalised Programming with Mr FGS is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Those interested in making changes to their exercise, lifestyle, dietary, supplement or medication regimens should consult a relevantly qualified and competent health care professional. Those who decide to apply or implement the Personalised Programming or any of the information, advice, and/or recommendations on this website do so knowingly and at their own risk. If you think you are experiencing a medical emergency call you doctor or ambulance immediately. The owner and any contributors to this site accept no responsibility or liability whatsoever for any harm caused, real or imagined, from the use or distribution of information found at FitGreyStrong. Please leave this site immediately if you, the reader, find any of these conditions not acceptable.
As with all program, results may vary. Exercise alone has been shown to be relatively ineffective at inducing weight loss and diet remains critically important. It is advisable to consult your healthcare professional before beginning any lifestyle change or if anything arises that is of concern or relates to questions of a medical nature.
Please note: Discount coupon codes are not valid for this service.
In my last research article review titled “Muscle strength gains during resistance exercise training are attenuated with soy compared with dairy or usual protein intake in older adults – part 1” (see here), no additional benefit for improvements in strength, body composition, physical function, or quality of life when additional protein from either dairy or soy versus usual protein intake were seen after 12 weeks of progressive resistance training exercise in healthy older adults.
The focus of this article – part 2 of this review – is to discuss the findings that suggest that increased soy protein intake attenuated improvements in muscular strength compared to dairy protein and usual protein. I want to explore some of the results of this study that are discordant with the conclusions reached by the authors. Their take-home message I believe is therefore misleading and misrepresents what the study actually showed.
The biggest problem with this is that the vast majority of media (print, TV, social media etc), websites, blogs and other avenues used to report on this study, haven’t taken the time to analyse or assess whether or not the conclusions reached are valid. In fact, when I Googled the net for websites, pages or blogs that wrote about, and reported the results of the study in question, I could not find ONE that had even questioned or scrutinised the conclusion against the actual results produced.
This highlights a bigger issue regarding the veracity of health, exercise, fitness and nutrition news that is reported and shared – following publication – in the blink of an eye. Whilst I do not want to explore this further today, it is certainly something that bothers me and something I would like to write about soon.
Let’s look at some of the issues with the conclusions reached by the authors of this paper.
Problem #1 – One of the main findings claimed to have been shown by this research was that:
Increased soy protein intake attenuated gains in muscle strength during resistance training in older adults compared with increased intake of dairy protein or usual protein intake” (pg. 27).
Now unless you read the whole study and scrutinised the results there would be no way of knowing if this conclusion is well-founded or not; so let’s have a look at the results table to see if this is a fair assessment of their data (click on table to expand).
Strength improvement results for each diet intervention
The first thing you’ll notice is that the only exercise that soy protein attenuated gains in muscle strength was leg press 8RM (RM; maximum weight lifted for eight repetitions); for all other exercises no differences were found for protein source and subsequent strength improvement. More specifically, there were no significant differences between the soy, diary and usual protein group for strength improvement in isometric knee extensor strength, handgrip strength, chest press, knee extension, lat pulldown and leg curl. Thus, strength training adaptation from resistance training in older adults for all exercises, bar one (leg press), was the same irrespective of the protein source provided. The significant difference found therefore for the sum total 8RM lifted for all 8RM exercises was most likely due to the difference in leg press 8RM. (Note: percentage improvement in lat pulldown 8RM was greater in usual protein vs dairy but with no difference vs soy; this doesn’t, however, detract from the core proposal above).
Leg Press for increasing lower body muscle strength
If that is the case, the question that needs to be asked is, why was this ignored and not explored in the discussion? There are certainly some intriguing possibilities regarding this result. Does soy protein, for example, possibly attenutate gains in lower body but not upper body strength? Is there any other explanation for the attenuated strength for Leg press and, if so, would that mean that there are essentially no differences between the source of the protein and the strength improvement? I’m not sure what mechanism of action you would propose to explain a differential for strength gain between lower and upper body when consuming soy versus dairy protein? The authors do hypothesise that the inhibition of strength gain due to soy protein could have been hormonally based by stating:
Instead, it is more likely that the attenuation of the strength increase in the HP-S group was due to some effect of the soy inhibiting the increase in strength. Soy foods not only contain soy protein, but also contain isoflavones, which exhibit estrogenic properties [Barnes 2012]. A recent study demonstrated that 14 days of soy protein supplementation in resistance trained young men during training reduced serum testosterone concentrations in the first 30 min post-exercise compared with whey protein or a carbohydrate control [Kraemer et al. 2013]. It was proposed that this blunted serum testosterone response might reduce the anabolic response in skeletal muscle, thus attenuating the accretion of contractile protein and muscle strength gains. This may explain the attenuated increase in strength gains observed in the HP-S group in the present study (pg. 32).
However, I don’t think that the abovementioned soy-induced reduction in serum testosterone has been shown to affect muscle contractile properties in an appendicular specific manner (i.e. lower body responds differently to upper body). Moreover, in contrast to the authors proposition above, post-exercise testosterone response does not appear to correlate with, nor is it in any way indicative of subsequent strength gains following resistance training as shown, for example, by the work of Morton and colleagues (2016).
Problem #2: Assessing the results listed in table 2 for Leg Press highlights another interesting difference between the soy and dairy protein groups. The baseline strength values for the dairy and usual protein groups are significantly lower than the soy protein group (55.0 vs 77.3 vs 56.6). In fact, the 8RM baseline strength value for the soy protein group is approximately 40% higher than the other protein groups. Such a large difference would have been unexpected following randomisation with most other baseline values relatively comparable. How this difference affected the statistical analysis is difficult to say but I would have liked the authors to discuss this to put such a baseline disparity into perspective.
Given what was discussed in problem number 1, a separate statistical analysis should have been conducted on all 8RM exercises with leg press 8RM excluded. This assessment would have been able to tease out if the attenuated strength gain seen in the leg press also applied to the 4 other exercises. Based on the data for each individual exercise (excluding leg press), no differences were observed; however, there may have been insufficient power to detect any real differences. By grouping these 8RM exercises together this question could have been answered. As it stands, soy-induced strength gain attenuation can only be claimed for the 8RM leg press.
Are functional strength gains limited by machine-based training?
In relation to the training sessions, what is not particularly clear is whether the participants trained one-on-one with their instructor in solitude or whether the sessions involved small groups. It is feasible that if participants trained individually and at the same time but with different instructors, or in small mixed groups, those allocated to the dairy and usual protein experimental diets may have inadvertently or surreptitiously observed what the ‘stronger’ leg press soy participants were lifting and been incentivised to ‘push’ that bit harder in an attempt to bridge the gap.
Final comments: Based on the results of this study, I would have worded the conclusion very differently to that which was put to print by the Thomson et al. Something like the following would have probably been more apt:
Increased soy protein intake appeared to attenuate gains in leg press muscle strength only, compared with increased dairy protein or usual protein intake. With all other exercises there were no notable differences. Further research is required to explore the possibility that soy protein may specifically inhibit lower body strength gains from resistance training in older adults.
Post-script: Following further analysis and publication of part 2 of this blog, I wrote a letter to the Editor of Clinical Nutrition Journal outlining, what I believed, were some of the flaws regarding the interpretation of the results of this trial. Upon peer review this was accepted for publication and can be found here. If you are unable to access this correspondence and the authors reply to my letter, please contact me and I should be able to assist.
References
Barnes S. (2004) Soy isoflavones-phytoestrogens and what else? J Nutr 134:1225S-8S.
Cermak et al. (2012) Protein supplementaiton augments the adaptrive response of skeletal muscle to resistance-type exercise training: a meta-analysis Am J Clin Nutr 96: 1454- 64.
KraemerWJ et al. (2013) The effects of soy and whey protein supplementation on acute hormonal reponses to resistance exercise in men. J Am Coll Nutr 32:66-74.
Morton RW, Oikawa SY, Wavell CG, Mazara N, McGlory C, Quadrilatero J, et al. Neither load nor systemic hormones determine resistance training-mediated hypertrophy or strength gains in resistance-trained young men. J Appl Physiol July 1, 2016;121:129-138.
Thomson et al. (2016) Muscle strength gains during resistance exercise training are attenuated with soy compared with dairy or usual protein intake in older adults: A randomized controlled trial. Clinical Nutrition. 35: 27-33
Disclaimer: All contents of the FitGreyStrong website/blog are provided for information and education purposes only. Those interested in making changes to their exercise, lifestyle, dietary, supplement or medication regimens should consult a relevantly qualified and competent health care professional. Those who decide to apply or implement any of the information, advice, and/or recommendations on this website do so knowingly and at their own risk. The owner and any contributors to this site accept no responsibility or liability whatsoever for any harm caused, real or imagined, from the use or distribution of information found at FitGreyStrong. Please leave this site immediately if you, the reader, find any of these conditions not acceptable.
