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6/1/2023 Newsletter

Nadolsky KZ. COUNTERPOINT: Artificial Sweeteners for Obesity-Better than Sugary Alternatives; Potentially a Solution. Endocr Pract. 2021 Oct;27(10):1056-1061. doi: 10.1016/j.eprac.2021.06.013. Epub 2021 Sep 3. PMID: 34481971.

Everyone has heard someone at some point in time say that regular soda is better for you than diet soda, namely because of the non nutritive sweeteners in diet drinks. While there is some evidence that on a population level consumption of non nutritive sweeteners has a higher risk for specific illnesses most dont account for age differences in participants, and other dietary intake of ultra processed foods in groups of people who consume non nutritive sweeteners (NNS) in high amounts. However, with obesities it seems these can be beneficial. Thus, they may prove beneficial for fitness related goals as well, as they provide sweet taste without the caloric content.

Typically obesities is a complex condition that results from a combination of food environment, genetics, dietary habits, social conditioning, socioeconomic status, among many other factors. While energy intake versus energy output is a big factor in weight loss, with obesities its not that simple given many external and internal factors interaction that can be beyond our volitional control. NNS typically include saccharin, aspartame, sucralose, stevia, ace K, and monk fruit. And NNS seem to provide benefits for those with obesities, although fraught with controversy.

Much of the observational data has methodological limitations when discussing safety of NNS. Finding a population of individuals who have dietary patterns in line with Dietary guidelines, and exercise habits in line with Activity Guidelines would only represent an extremely small niche within the larger general population. There are biological plausibility, and some mechanisms for some of the concerns with NNS but many do not pan out in literature, and some of the safety concerns are warranted but if true would seriously call into question methods used to ensure safety of the food supply as a whole.

It may be more concerning with the immediate effects of increased calorie consumption when using sugar versus NNS in cases where someone is not closely monitoring their caloric intake. As some studies show using NNS can result in significant weight loss, loss of fat mass, and loss of that fat mass around the mid section which may have more implications in overall health due to negative effects of visceral fat. Also NNS consumption without tracking calories either results in no compensation of calories eaten or sometimes a reduction in caloric intake with some studies showing in the short term 10-12 lb weight loss across 12 weeks when utilizing NNS and groups using NNS maintaining that weight loss over a year, or in some cases losing more weight. Many studies also show no or little impact on insulin response following NNS intake which is a common myth that it would spike insulin levels. NNS even when combined with glucose also seems to result in better markers for metabolic factors even in those with risk factors such as older age, high BMI, and Diabetes. Also evidence, particularly with stevia and diet carbonated drinks suggests that these tend to reduce caloric intake on average versus increasing calorie seeking behaviors like many people claim to be true.

Furthermore, NNS are often included in many meal replacement shakes which have as interventions some of the best data to support reduction of weight and benefits on diabetes. In many studies the use of meal replacement shakes results in significant weight loss and remission of non insulin dependent diabetes.

There are some pending questions about the overall safety of NNS in specific instances and on a population level especially in high amounts given the dietary pattern and exercise habits of the population as a whole. But on an individual and interventional level NNS show safety and benefit especially when it comes to helping reduce added sugar intake and reduction of caloric intake. While we may not want to go wild with the use of NNS, overall they do not deserve to be as demonized as they are in the general culture. Especially, given the benefits they do offer as a tool towards improving metabolic health and maintain a metabolic health and reducing adiposity.

Van Cutsem J, Marcora S, De Pauw K, Bailey S, Meeusen R, Roelands B. The Effects of Mental Fatigue on Physical Performance: A Systematic Review. Sports Med. 2017 Aug;47(8):1569-1588. doi: 10.1007/s40279-016-0672-0. PMID: 28044281.

Mental fatigue (MF) is a state caused by prolonged periods of demanding cognitive task performance. In our daily lives MF is associated with decline in workplace performance and increase in overall errors when performing tasks. MF can manifest by subjective feelings, behavior change and psychologically. Usually it is associated with an increase in feelings of being fatigued/tired, lack of energy, motivation, and reduced alertness. In some instances we can counter mental fatigue with an increase in motivation, for example, taking a pre workout or finding a song we like.

While mental fatigue seems to have a lesser effect on resistance training, it appears to have more of an impact on endurance related tasks. It seems that all-out exercise where we do not have to think about pacing ourselves is overall less affected. It is postulated that this is because of less decisions being made about pacing, and other factors. We might also see that mental fatigue also impacts more technical training and or complex lifts. It also appears that shorter mental exertion is not sufficient to induce mental fatigue.

Evidence suggests that for endurance type exercise there is an increase in time to completion of task, decreased self pace velocity, and power output and distances covered in studies reviewed. There is also usually higher ratings of RPE, and heart rate, and generally the perception of fatigue is higher following MF inducing tasks.

Cao S, Geok SK, Roslan S, Qian S, Sun H, Lam SK, Liu J. Mindfulness-Based Interventions for the Recovery of Mental Fatigue: A Systematic Review. Int J Environ Res Public Health. 2022 Jun 26;19(13):7825. doi: 10.3390/ijerph19137825. PMID: 35805484; PMCID: PMC9265434.

MF is associated with a variety of resource depletion, meaning that will power and decision making can be impaired due to mental fatigue. Literature suggests a person is more likely to “break” diets, indulge in alcohol, cheat, and fail to manage emotions, as well as perform worse on intellectual task tests due to MF. Thus its clear that MF impairs impulse control.

It appears that mindfulness based interventions can help to combat MF. Mindfulness is originally sourced from Buddhism and is based on the awareness that comes from paying attention to objects, feelings, surroundings, actions etc, on purpose without judgment of the way that it unfolds. The 4 main pillars mentioned in this study are awareness, attention, present focus, and acceptance). Successfully partaking in mindfulness practice often results in having experiences without judging or evaluating them or acting on the sensation. This appears to impact attention and self control and helps counteract MF. Mindfulness seems to impact positive performance in a number of tasks from hand gripping, planking, free throws and many other tasks/outcomes.

Mindfulness can be as simple as described above, involving exercises such as body scans, deep breathing, listening to music, journaling, or guided audio/video mindfulness practices. Some resources can be found searching youtube, the calm app, Insight timer app among others. It can even mean just sitting quietly and experiencing the world around you for several minutes at a time, as varying lengths can have positive effects.

Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ. Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy: A Systematic Review with Meta-analysis. Sports Med. 2022 Nov 5. doi: 10.1007/s40279-022-01784-y. Epub ahead of print. PMID: 36334240.

Overall most factors we adjust when considering training for hypertrophy include reps, sets, volume, frequency and load. These seem to be some of the more important factors to consider, although proximity to failure (PTF) can impact the mechanical tension seen when lifting, which is currently considered very important for triggering growth. Typically failure is considered as momentary failure or the point at which you cannot continue in the concentric portion of a lift through the full arc of planned movement.

Practically most individuals do not take all sets to failure, as this generates a larger amount of fatigue, than training to non failure, especially over multiple sets. And thus far most research suggests it is not superior for growth, especially when volume is equated in training. So it seems that there is not a direct relationship between training to failure and muscle growth, likely due to the impact other factors have on hypertrophy.

The authors of this article also subgrouped definitions of training to failure, as some articles used different definitions of failure. Some would use momentary failure, set failure (anything outside momentary failure, and failure based on velocity loss profiles.

In the groups training to set failure there was trivial-small effect sizes. When momentary muscular failure was used as the definition of failure effect sizes were so small its not enough of a difference to have any meaning. When set failure is used the effect size is small, which is typically meaning not worth losing sleep over. Typically only effect sizes that are moderate-large would be worth regularly considering. For example, a small effect size is worth considering if every other factor that would have more impact is in place already.

At this point given the state of the literature and lack of consensus on proximities to failure used in research, and definitions of failure often lacking standardization, it is difficult to say which POF would maximize hypertrophy. However, there is a noted difference that when number of sets are matched per week the effects of training to failure wash out more in the effects it has on growth. Although, if loads being used are very light, 50% of 1RM or less, training to momentary failure seems to have a much large impact on hypertrophy. Similarly, when looking at velocity based training, higher velocity (25% or more with most being near 40% with largest effects) losses have a larger effect on growth, but not significantly more than moderate losses (20-25% loss).

The below figure from the study illustrates the concepts about why high velocity loss training, and lots of training to momentary failure likely do not elicit significantly more growth than non failure and moderate velocity loss training.

Failure training is not to be completely neglected however in training. It can provide benefits practically, for example with exercises with low set volume, less than 5 per week, or that are being trained at low frequencies. Furthermore to reduce the impact of neuromuscular fatigue that likely causes non-failure and failure training to result in similar growth it may be wise to perform this on isolation exercises and more towards the end of a session for that muscle group. Failure training and high velocity loss training does have its place in training but as a whole individual factors need to be considered when utilizing it in training.

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