I read the review article (abstract; full article) on the anticipatory regulation of performance and pacing strategies by Dr R Tucker in the June edition of BJSM with great interest. The idea that there is a part of the brain, as yet undiscovered, which enables one to judge the optimal work rate for a given task, is an intriguing one.

From a Darwinian view point, the idea of there being a template in the brain that one could draw upon in determining pacing strategy, carries great merit. Anthropologists have learnt of a hunting strategy used by Bushmen from Southern Africa in which the prey, such as a Kudo, is chased for many hours until it collapses in exhaustion. The Bushmen pace themselves, such that they do not succumb to exhaustion, and are able to follow the tracks of the animal when they lose sight of it. The same principle can be seen with the hunting behaviour of wolves. Having spotted a weak member of a herd of elk or other deer, they will chase it for hours on end if necessary.

It is obvious that the most successful hunters will be those who can judge their pace the best. The genes of these hunters are more likely to be passed through to the next generation. An athlete’s ability to judge pace is therefore likely to be the consequence of millions of years of mammalian evolution.

Dr. Fergus J. Dignan

The following is a letter to BJSM from Ralph S. Bovard MD:

Dear BJSM,

I have a question regarding the use of autologous platelet rich plasma (PRP) injections for tendinopathies of various sorts.  This procedure has been gaining favor with sports medicine clinicians for use in athletes with tendon injuries that are slow to respond or resistant to conservative therapies.  Despite the fact that it would appear to be a seemingly innocent matter of re-injecting one’s own spun down blood products, the World Anti-Doping Agency (WADA) most recent 2009 Prohibited List, if taken literally, would make it an illegal procedure for international competition or national competition under any NGB’s who endorse WADA.  The culprit substances in this case would be growth hormone (GH), Insulin-like Growth Factors (IGF-1), and Mechano Growth Factors (MGF’s).

The relevant section from the code is included below:

S2. HORMONES AND RELATED SUBSTANCES

The following substances and their releasing factors, are prohibited:
1. Erythropoiesis-Stimulating Agents (e.g. erythropoietin (EPO), darbepoietin (dEPO), hematide);
2. Growth Hormone (GH), Insulin-like Growth Factors (e.g. IGF-1), Mechano Growth Factors (MGFs);
3. Chorionic Gonadotrophin (CG) and Luteinizing Hormone (LH) in males;
4. Insulins;
5. Corticotrophins;
and other substances with similar chemical structure or similar biological effect(s).

[Comment to class S2:
Unless the Athlete can demonstrate that the concentration was due to a physiological or pathological condition, a Sample will be deemed to contain a Prohibited Substance (as listed above) where the concentration of the Prohibited Substance or its metabolites and/or relevant ratios or markers in the Athlete's Sample satisfies positivity criteria established by WADA or otherwise so exceeds the range of values normally found in humans that it is unlikely to be consistent with normal endogenous production.

If a laboratory reports, using a reliable analytical method, that the Prohibited Substance is of exogenous origin, the Sample will be deemed to contain a Prohibited Substance and shall be reported as an Adverse Analytical Finding.] The Prohibited List 2009 20 September 2008

It would thus seem that PRP is banned under “Class S2: Hormones and Related Substances”, rather than under “M1: Blood Doping”.  The re-delivery of blood is prohibited under blood doping; regardless of whether it is endogenous or exogenous.  There is no mention or attempt to discriminate between blood products that are re-injected immediately into soft tissues versus those that are shelved and re-infused by IV weeks or months later in the typical manner of “blood doping”.

The argument is made that while PRP indeed delivers  the athletes own growth factors to a musculoskeletal site, the platelets are concentrated to a level not normally achieved physiologically, and they are activated either chemically (via calcium addition) or mechanically (centrifugation) and thus degranulate  rapidly and deliver a bolus of factors never “normally” or physiologically achieved.

Given this stance it would seem that the use of platelet rich plasma injections is clearly prohibited.   Tendinopathies are not life threatening or otherwise serious medical conditions and as such the rational of applying for a therapeutic use exemption (TUE) would seem a difficult argument.   Yet how would PRP injections be detected other than by admission?  What is the opinion of the BJSM readership regarding this topic?

Thank you,

Raph S. Bovard MD

In response to “What factors are associated with physical activity in older people, assessed objectively by accelerometry?” (abstract, full article):

We have read with interest the recently reported accelerometer study of physical activity in community-living seniors in Oxfordshire (1).

Subjects were observed for 7 days, apparently in the winter or the spring, although the only clue to the important question of season is that invitations were sent out over a 20-week period, beginning in September of 2006. In discussing their data, the authors claim (p. 446) “This is the first moderately sized population-based study of older people published to date with objective PA measures and a broad range of health, psychological and anthropometric variables.”

In fact, a much more extensive community study of seniors aged 65-99 years has been conducted previously, in the Japanese community of Nakanojo. Many of the key findings from the Nakanojo Study have been published, and are summarized in a recent review (2). The Japanese subjects were monitored 24 hours per day for an entire year, thus avoiding problems from seasonal variations in physical activity (3-6). Perhaps in part because seasonal effects are quite large in this age group, the average step counts over the whole year were somewhat higher than the 6443 steps/day reported by Harris et al. (1), particularly in the male subjects. It would be interesting to have for comparison British data that also covers an entire year. Like Harris et al. (1), we found associations of step counts with age, sex, body build, physical, metabolic and psychological health among other environmental, geographic and psycho- social variables, and our data support the view that in Asia, as in Europe, many seniors are currently taking substantially less than the recommended daily dose of physical activity.

Yukitoshi Aoyagi and Roy J. Shephard, Researchers, Tokyo Metropolitan Institute of Gerontology, Japan.

REFERENCES

1. Harris TJ, Owen CG, Victor CR, et al. What factors are associated with physical activity in older people, assessed objectively by accelerometry?  Br J Sports Med 2009; 43: 442-450.

2. Aoyagi Y, Shephard RJ. Steps per day. The road to senior health?
Sports Med 2009; 39: 423-438.

3. Togo F, Watanabe E, Park H, et al. Meteorology and the physical activity of the elderly: the Nakanojo Study. Int J Biometeorol 2005; 50:
83-89.

4. Togo F, Watanabe E, Park H, et al. How many days of pedometer use predict the annual activity of the elderly reliably? Med Sci Sports Exerc 2008; 40: 1058-1064.

5. Yasunaga A, Togo F, Watanabe E, et al. Sex, age, season, and habitual physical activity of older Japanese: the Nakanojo Study. J Aging Phys Act 2008; 16: 3-13.

6. Shephard RJ, Aoyagi Y. Seasonal variations in physical activity and implications for human health. Eur J Appl Physiol 2009; in press. doi:
10.1007/s00421-009-1127-1.