Recent eLetters

Pre-participation screening in competitive athletes in Portugal has been compulsory for more than 40 years. Yearly ECG was introduced in the screening at about the same time as in Italy, for all athletes evaluated at the Sports Medicine Centres in Portugal. The very rare cases of sudden cardiovascular death that have ocurred in the past 25 years in Portugal were not screened at the Centres or had further cardiovascular evaluation pending, and threfore were not qualified for practice. Several athletes have been disqualified from sports participation for cardiovascular reasons, most of them were further investigated because of rest ECG changes findings. We strongly favour the use of 12 lead ECG in the pre- participation screening process. Presently, we routinely screen about 20.000 athletes per year in the 3 Sports Medicine Centres in Portugal.

Conflict of Interest:

None declared

This outstanding body of research is a watershed in the fight against ACL-injuries. This group should be richly commended for this excellent work.

The work points to (a priori) how, in the case of alpine skiing, excessive abduction loading / valgus torque of the lower leg structure relative to the upper leg (about the knee) can be truncated by "detaching" the imposing load from the point of load application at the playing surface in the direction of the applied load. E.G., if the medial load that applies abduction to the lower leg can be "released" from the lower leg -- the abduction / valgus loading will dissipate. An alpine ski- binding with this capability (via lateral heel release) will provide this capability when the applied load is "released" (when the applied abduction load approaches a pre-determined level that is well below the elastic limit of the acl but which level is above that which is needed to provide "controlled" skiing maneuvers). Such a binding exists, today, and a prospective intervention study should be considered to study its merits for skiers.

Rick Howell, CEO, Howell Product Development, Inc., Stowe, Vermont, USA

Conflict of Interest:

Inventor of alpine ski-binding with independently adjustable, non-inadvertant abduction release in response to excessive valgus loading, but am presently cut-off from financial gain in this IP due to on-going litigation re ownership rights.

Dear Editor

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) �gThis 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.�h

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

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.

Dear Editor

We appreciate the thoughtful review of our manuscript by Hancock, Ste -Marie and Young.(1) In this brief response, we reconsider the issues raised in their review and continue the discussion of relative age effects in National Hockey League (NHL) draftees.

REGARDING THE APPROPRIATE USE OF CUTOFF DATES.

Hancock et al. proposed that the more appropriate method for examining relative age effects in NHL draft players was to use the age cutoff criterion established by the NHL (September 16th). Our original analyses(2) utilized the age cutoff from the Hockey Canada and Hockey USA governing bodies (January 1st). Although the cutoff used by Hancock et al. seems reasonable, we submit that our original analyses were more appropriate because the proposed mechanisms of relative age effects are known to originate early in an athlete’s development.(3)

In sport, relative age attainment differentials are proposed to result from physical maturation differences among individuals during growth and development. (4) Specifically, those born shortly after the cut -off date established by sport governing bodies typically display more mature physical characteristics compared to those born later in the year. (5) Greater height, strength, speed and power not only relate to maturity, but also provide physical attributes that underpin performance in many sports. As a result, earlier-born, more mature individuals are more likely to dominate youth sport, be identified as ‘outstanding’ and be selected by scouts and coaches for representative sport competition. (4)

More competitive levels of sport participation are associated with dramatic changes in the practice environment. Here, selected athletes access practice more frequently and dedicate an increasingly significant proportion of weekly time to training with more highly qualified and specialized coaches to facilitate continued development. Thus selection and access to quality practice propagate relative age effects well into the senior years, explaining why discrepancies in birth date tendencies have been reported repeatedly across professional sports.(4) Interestingly, a recent meta-analysis by our research team found that relative age effects were strongest in adolescence and diminished in adulthood. (4)

In summary, the cutoff dates associated with early development drive relative age effects, not the cutoff date used for the NHL draft. Altering the cutoff date as we saw from Hancock et al. should have little influence on the overall effect. Their re-analysis indicates the largest representation was in birth quarter two followed by birth quarter three, which, as they showed, corresponds better to a relative age effect originating from the Hockey Canada and Hockey USA cutoff date of January 1st than September 1st.

REGARDING THE USE OF ALL DRAFT ROUNDS

Hancock et al criticized our choice to use all seven rounds of the draft for our relative age analyses on the basis that later rounds are made up of lower quality players. This seems like splitting hairs to us, as this rationale could also be used to justify using only round one instead of rounds two to four or the first 10 players of round one versus the remaining 20 players in round one. Moreover, our paper was written to demonstrate that the relative age effect explained some of the results for the NHL draft, not the performance of the draftees after they had entered the NHL. We defend our original choice on the basis that any selection in the NHL represents a reasonable level of expertise to examine the relative age effect in this population. Furthermore, and perhaps more interesting, an additional analysis of our data comparing relative age distributions for rounds one to four with rounds five to nine (up to 2005 the NHL draft had nine rounds), noted a slightly stronger relative age effect in later rounds than earlier rounds (Cramér’s V = 0.08 for rounds 1-4 and 0.13 for rounds 5-9).

REGARDING DRAFT VERSUS OVERALL SELECTION FOR SPEARMAN CORRELATION

The rationale for using an athlete’s overall selection in the draft versus round number is reasonable, as it adds additional depth to the selection variable. However, coaches, athletes and spectators rarely talk about athletes in terms of what their overall selection was – more often the overall draft round number is the characteristic of interest. Teams often have differing strategies for how they choose players in the draft (e.g., drafting to win the Stanley Cup vs. drafting for team development). As a result, players ranked highly by one team might not be considered at all by another. Removing draft round number assumes a) that each team uses the same strategy for how they choose their draft picks and b) that players can be easily rank-ordered and are equivalent from team to team. We defend our original analysis as being perhaps more relevant to the specific practices used by each team during the draft, although we appreciate the additional statistical depth that might be added by Hancock et al.’s method. The lack of consistency between our analyses and theirs is cause for concern, however, and we encourage future research in the area to elucidate these contradictory findings.

In summary, these studies continue to highlight the effects of secondary factors on long-term athlete development.

Joseph Baker

References

1. Hancock, D. J., Ste-Marie, D. M., Young, B. W. Birth date and birth place effects in National Hockey League draftees 2000-2005: Comments on Baker and Logan (2007). Br J Sports Med 2008; 42: 948-949.

2. Baker, J. Logan, A. J. Developmental contexts and sporting success: Birthdate and birthplace effects in NHL draftees 2000-2005. Br J Sports Med 2007; 41: 515-517.

3. Barnsley, R. H., Thompson, A. H. Birthdate and success in minor hockey: The key to the NHL. Can J Behav Sci 1988; 20 167-176.

4. Cobley, S., Baker, J., Wattie, N. McKenna, J. Annual age grouping and athlete development: A meta- analytical review of relative age effects in sport. Sports Med 2009; 39 235-256.

5. Sherar LB, Baxter-Jones ADG, Faulkner RA, et al. Does physical maturity and birth date predict talent in male youth ice hockey players? J Sports Sci 2007; 25: 879-86