The main finding of the present study is that StemSport did not accelerate recovery from an acute bout of single upper-arm eccentric exercise in non-resistance trained adults.
StemSport contains the fresh water blue-green algae, AFA, which has been studied primarily for its antioxidant/anti-inflammatory properties . The effects of AFA on inflammation are limited to animal studies . To our knowledge, the present study is the first to examine the effects of AFA on systemic inflammation and other markers of DOMS in humans.
Most recently, AFA has been suggested to be a potential bone marrow stem cell mobilizer . Studies from Jensen et al. (2007) and Drapeau et al. (2010) indicate that a novel compound from AFA appears to play a role in the release of bone marrow stem cells into the circulation, and it has been suggested that bone marrow-derived stem cells may accelerate the tissue regeneration process in some animal models of injury [7, 8]. It has been further hypothesized that AFA plays a role in recovery from muscle damaging exercise via increasing bone marrow-derived stem cells, although this has not been tested directly in humans .
In a placebo-controlled double-blind crossover study, a 5:1 concentrate of AFA concentrate fed to healthy volunteers (n = 12) produced a 25 ± 1% increase in number of circulating CD34+ stem cells at 60 minutes (p < 0.0001) . In contrast, the placebo only produced minor fluctuations in levels of stem cells in the blood circulation over 2 hours. It has been hypothesized that acute increases in post-exercise circulating levels of stem cells may be beneficial for tissue regeneration and recovery . Stem cell counts (e.g. CD34+) were not specifically measured in the present study, however, given that recovery of muscle function was similar between conditions, it is unlikely that any AFA induced change in circulating stem cells plays a major role in recovery from upper arm DOMS.
In agreement with previous studies in the literature, we did not observe an association between circulating inflammatory markers and others markers of DOMS (e.g. pain and tenderness) [12, 13]. However, this may be related to the relatively small muscle mass utilized in our DOMS protocol which may not have been a potent stimulus for increasing circulating cytokines. Future studies should attempt to study AFA supplementation in response to an eccentric exercise protocol designed to produce a much larger inflammatory response (i.e. downhill running).
Leukocytes, neutrophils, and monocytes/macrophages are attracted to damaged tissue within hours of tissue injury and remain present for up to 24 hours, or as has been shown in macrophages, up to 14 days . Neutrophils and macrophages assist in degradation of damaged muscle tissue primarily through production of reactive oxygen and nitrogen species (RONS). Degradation of damaged tissue is also initiated by the expression of many local pro- and anti-inflammatory cytokines (e.g. IL-6, TNF-α, IL-1β, etc.). Circulating IL-6, which has both pro- and anti-inflammatory functions, is related to the level of DOMS, and there is some debate as to whether the post-exercise IL-6 response is required for muscle adaptation . Elevated levels of IL-6 persist for at least 48 hours after eccentric upper arm exercise . Less is known about the post-exercise time course of TNF-α, although studies have detected elevated levels of TNF-α for up to 5 days during DOMS . The present data do not support a role of AFA in suppressing circulating levels of IL-6, TNF-α, or CRP in humans in the basal state or in response to an acute bout of upper arm eccentric exercise designed to induce DOMS.
Besides AFA, StemSport contains a proprietary blend of several herbal substances potential antioxidant or anti-inflammatory properties (Cat’s Claw , Mangosteen juice , Radix Rehmanniae Preparata , Nattokinase [19, 20], Serrapeptase and , and Curcumin ; see Table 1). For example, Curcumin, an ingredient derived from the spice Tumeric, has been shown in a few studies to reduce DOMS related pain and swelling [17, 22] and has a potential role is reducing obesity-related inflammation. However, our data tend to agree with the majority of studies in the literature which show that oral antioxidant supplementation has minimal to no effect on reducing subjective ratings of pain, tissue swelling, or decrements in muscle function after a bout of eccentric exercise [2, 23–25]. It should be noted that data in the literature now support an inhibitory effect of oral antioxidant supplementation on the skeletal muscle adaptations exercise . In addition, supplementation with the popular antioxidant ascorbic acid has been shown to delay the recovery process .
A possible limitation of this study was the use of DOMS to examine the utility of StemSport. It is possible that the amount of tissue damage associated with the DOMS protocol may have been too great for StemSport to have an effect. It is possible that if a less disruptive regimen was applied (e.g. strength training) StemSport supplementation may enhance chronic adaptations to whole body resistance training. Also, future studies may consider investigating the effects of AFA, independent or in combination with the other herbal substances. Strengths include study design (placebo-controlled, double-blinded, randomized trial) and measurement of both subjective markers of DOMS as well as bio-markers of the inflammatory process.