Progressive RET is a well-established workout method that not only improves athletic outcomes, but is also said to support muscle function and overall health of non-athletes.
Sphaeranthus indicus (East Indian globe thistle) flower and Mangifera indica (mango) tree bark are widely used in Ayurvedic medicine due to their immunomodulatory, antioxidant, and anti-inflammatory properties.
A randomised, double-blind, placebo-controlled study funded by General Nutrition Centre Inc (GNC) sought to elucidate the effect of a S. indicus and M. indica extract blend (SMI) on RET outcomes.
SMI is commercially available as GNC’s MyoTOR and PLT Health Solutions’ RipFACTOR.
A total of 99 men completed the trial after they were randomly assigned to one of four groups: (A1) 425mg of SMI and one RET set, (A2) 850mg of SMI and one RET set, (P1) placebo and one RET set, and (P2) placebo and two RET sets.
The participants were asked to consume two capsules every morning for 56 days.
The RET set included six to eight bench press (BP) and leg extension (LE) repetitions, and was carried out three times a week during the intervention period.
It was found that all groups significantly (p < 0.05) improved BP strength from baseline, but the SMI groups lifted more weight than the placebo groups.
In addition, total muscle strength of both A1 and A2 groups increased compared to P1 (p < 0.001) at all measured time points.
Notably, A2 demonstrated significantly (p < 0.05) more strength compared to P1 at all time points, and compared to P2 on days 28 and 56.
Muscle endurance was measured as repetitions to failure (RTF), which was determined by the maximal number of repetitions a participant completed when lifting 80% of the established baseline — progressive one repetition maximum (1-RM) — until failure.
All groups showed improved muscular endurance, as the number of BP-RTF and LE-RTF increased over time (p < 0.001 for each group).
A2 significantly (p < 0.05) improved BP-RTF compared to P1 on days 28 and 56, and compared to P2 on day 56. For LE-RTF, a treatment effect started showing on day 28 (p = 0.071) but only reached significance (p = 0.005) on day 56.
Furthermore, only A1 and A2 had significantly elevated serum values of total testosterone (TT) and free testosterone (FT) from baseline to day 56. The final FT and TT values for both groups were significantly raised compared to P1, but not P2.
On the other hand, cortisol levels in A2 were found to be lower than P2 (p < 0.05).
“Overall, daily supplementation with either 425 or 850mg of SMI was well-tolerated and accentuated muscle adaptation when used by healthy young men in a progressive eight-week RET programme,” the authors wrote.
The inclusion of a second placebo group underscores that the significant differences between the supplementation and placebo groups were not simply the results of different physical efforts.
“In fact, it affirms the notion that the efficacy of SMI was comparable to performing an additional set of exercises in untrained individuals.
“This suggests that SMI supplementation may be beneficial for other populations seeking to augment muscle responses to RET — for example, those who habitually participate in RET but whose adaptive responses have stalled.”
Potential to benefit wider populations
During RET, muscle fibres contract against weighted loads, creating mechanical signals that converge alongside other intracellular signals onto the protein kinase mTOR, which is closely involved in directing the rate of post-exercise muscle protein synthesis.
However, RET-generated mechanical signalling can result in drastically different strength outcomes between individuals, even when their trainings are of similar intensity.
Therefore, people engaged in weight lifting often modify their diet and/or use dietary supplements in an attempt to facilitate anabolic responses to their training efforts.
Safe, conveniently dosed, and plant-based products are also increasingly being explored for their ability to support RET responses.
Mangiferin, a bioactive component derived primarily from M. indica, may activate nitric oxide (NO) within vascular endothelial cells.
NO is a signalling molecule that can influence mitochondrial function and modulate skeletal muscle activity, and NO precursors could stimulate muscle protein synthesis and muscle growth, particularly when combined with exercise.
Additionally, S. indicus and M. indica are both known for their antioxidant properties and may help scavenge oxidants generated in the actively contracting muscles.
Despite the elevation of TT and FT in the A1 and A2 groups in this study, RET has been shown to bring no or limited transient increase in testosterone levels in women.
As the study only included male participants, the researchers said that future studies should examine how SMI might affect muscular adaptive responses to RET in healthy women, and specifically in women experiencing peri- and postmenopause.
The effect of testosterone is also influenced by circulating cortisol, which plays a fundamental role in skeletal muscle adaptive responses by promoting lipolysis and proteolysis.
A higher testosterone/cortisol (T/C) ratio represents an improved balance between the anabolic and catabolic status of the body, whereas a decreasing T/C ratio often marks exercise-induced stress, physiological strain, and inadequate post-exercise recovery.
Although cortisol levels fell in the supplemented groups, the overall increased T/C ratio in these participants suggests that SMI may improve adaptation to RET regimens.
“Muscle strength and functionality improve a wide array of health outcomes, so further research should be conducted to investigate if similar outcomes are seen in older adults, where muscular atrophy and sarcopenia are increasingly reported to lead to reduced functional capacity, increased frailty, and progressive disability.”
Source: Frontiers in Nutrition
https://doi.org/10.3389/fnut.2024.1393917
“A botanical extract blend of Mangifera indica and Sphaeranthus indicus combined with resistance exercise training improves muscle strength and endurance over exercise alone in young men: a randomized, blinded, placebo-controlled trial”
Authors: Dawna Salter, et al
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