Sunshine and Peak Performance

Phys Ed: Can Vitamin D Improve Your Athletic Performance?

2009-09-23T06:06:00.002-04:00

Interesting article in the New York Times:

Although few studies have looked closely at the issue of Vitamin D and athletic performance, those that have are suggestive. A series of strange but evocative studies undertaken decades ago in Russia and Germany, for instance, hint that the Eastern Bloc nations may have depended in part on sunlamps and Vitamin D to produce their preternaturally well-muscled and world-beating athletes. In one of the studies, four Russian sprinters were doused with artificial, ultraviolet light. Another group wasn’t. Both trained identically for the 100-meter dash. The control group lowered their sprint times by 1.7 percent. The radiated runners, in comparison, improved by an impressive 7.4 percent.

More recently, when researchers tested the vertical jumping ability of a small group of adolescent athletes, Larson-Meyer says, “they found that those who had the lowest levels of Vitamin D tended not to jump as high,” intimating that too little of the nutrient may impair muscle power. Low levels might also contribute to sports injuries, in part because Vitamin D is so important for bone and muscle health. In a Creighton University study of female naval recruits, stress fractures were reduced significantly after the women started taking supplements of Vitamin D and calcium.

A number of recent studies also have shown that, among athletes who train outside year-round, maximal oxygen intake tends to be highest in late summer, Johnson says. The athletes, in other words, are fittest in August, when ultraviolet radiation from the sun is at its zenith. They often then experience an abrupt drop in maximal oxygen intake, beginning as early as September, even thought they continue to train just as hard. This decline coincides with the autumnal lengthening of the angle of sunlight. Less ultraviolet radiation reaches the earth and, apparently, sports performance suffers.

First Round NFL Draft Picks

2009-05-05T21:20:00.005-04:00

#1st Round = 0.48xUVI - 1.17
R2 = 0.60

From the 2000 draft to the 2009 draft there's a pretty good correlation between a state's Ultra Violet Index (UVI) and #1 Round NFL Picks Per Million (PPM) population in that state:

UVI PPM STATE
7.15 2.95 Louisiana
7.70 2.56 Florida
5.80 1.65 Georgia
4.47 1.73 NEW JERSEY
5.19 1.54 Virginia
5.49 1.37 Oklahoma
5.89 1.23 Texas
4.46 1.24 Maryland
4.07 1.13 Ohio
5.23 1.30 North Carolina
6.45 0.84 California
4.02 0.70 Michigan
3.95 0.53 Wisconsin
4.08 0.48 Pennsylvania
4.06 0.23 Illinois

A reason for the correlation may be that Vitamin D enhances athletic performance.

If I Was a Horseman - by E. Abraham Ola

2009-02-11T20:45:00.001-05:00

Animals need sunshine too:

If I was a horseman, I would know that a horse (or human) standing unnaturally still and stiff in a tight space like a racetrack stall for 23 hours per day is susceptible to arthritic conditions. I would know that horses need an hour afternoon walk in the sun to keep their limbs mobile and to receive some of the vital natural vitamin D that helps keep horses sound and healthy. I would provide small sun-yards for my racehorses so that weather permitting, they could spend a second hour in the sun each day, rather than spending 23 hours locked in far too small a stall while breathing virus- and bacteria-laden air.

Vitamin D Linked to Muscle Power

2009-02-11T20:35:00.003-05:00

More on the sunshine vitamin and physical performance:

MANCHESTER, England, Feb. 5 -- Vitamin D may play a key role in muscle function in adolescent girls, researchers here said.

Serum levels of 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) were significantly associated with muscle force and power in girls ages 12 to 14, Kate Ward, Ph.D., of the University of Manchester, and colleagues reported in the February issue of the Journal of Clinical Endocrinology & Metabolism.

"We know vitamin D deficiency can weaken the muscular and skeletal systems, but until now, little was known about the relationship of vitamin D with muscle power and force," Dr. Ward said.

Sunshine and the Elderly

2008-02-24T10:17:00.002-05:00

Peak performance isn’t just for elite athletes. While Vitamin D may make a difference in performance for those competing at the highest levels, it can also make a difference for the rest of us seeking to improve or maintain physical performance in our daily lives.

According to a recent New York Times article:

Last year, a 15-member team of nutrition experts noted in The American Journal of Clinical Nutrition that “randomized trials using the currently recommended intakes of 400 I.U. vitamin D a day have shown no appreciable reduction in fracture risk.”

“In contrast,” the experts continued, “trials using 700 to 800 I.U. found less fracture incidence, with and without supplemental calcium. This change may result from both improved bone health and reduction in falls due to greater muscle strength.”

A Swiss study of women in their 80s found greater leg strength and half as many falls among those who took 800 I.U. of vitamin D a day for three months along with 1,200 milligrams of calcium, compared with women who took just calcium. Greater strength and better balance have been found in older people with high blood levels of vitamin D.

Dr. John Cannell of the Vitamin D Council notes in his newsletter, Why Athletic Performance Matters, that:

Many people don't realize how fatal falls can be in the elderly. In 2003, the CDC reported that 13,700 persons over 65 died from falls in the USA, with 1.8 million ending up in emergency rooms for treatment of nonfatal injuries from falls. Falls cause the majority of hip fractures which, if they don't result in death, often result in admission to a nursing home. That's 13,700 deaths, hundreds of thousands of surgeries, countless nursing home admissions, and tens of billions in health care costs every year—all from impaired athletic performance. That's why it matters.

A Reuters report on how Vitamin D affects physical function in elderly, finds that "Older men and women who fail to get enough vitamin D -- either from their diets or exposure to the sun -- are at heightened risk for muscle weakness and poor physical performance, a study shows. This is troubling, researchers say, given the high numbers of older folks who are deficient in vitamin D." According to research done by Dr. Denise K. Houston at the Wake Forest University of Medicine: "...physical performance and grip strength were 5 to 10 percent lower in people with low blood levels of vitamin D levels, compared with those with normal levels."

However simply getting more exposure to the sun may not be enough without other lifestyle changes. Being overweight can reduce Vitamin D levels in the blood according to this Science Daily report:

It's not yet clear why overweight elderly adults have low levels of vitamin D in their blood. However, researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University (USDA HNRCA) have found that lack of sun exposure may not account for low levels of vitamin D in elders who are overweight. ... "The most likely explanation seems to be that vitamin D is sequestered in fat tissue, reducing its entry into the blood."

Sunshine and PGA Tour Wins

2008-02-17T11:28:00.004-05:00

No slight to Arnie and Jack, but the southern states have produced more PGA Tour winners since 1960 than the northern states. There are probably numerous reasons for this including more time to practice and play in warmer southern climates. Most top PGA Tour pros live in southern states and play the same courses during a season. However they differ in where they were born and it appears that those born in the south have a better chance for success as a PGA Tour Pro.

Being outdoors frequently provides exposure to sunlight which produces Vitamin D, a potent steroid hormone. This may also be a factor in the south's advantage in golf. The correlation between population adjusted number of top pro golfers and the UV Index in their birth states is similar to what we found for top (Division 1A) college football players (see Football’s Southern Exposure). However in terms of sheer numbers, top pro golfers are relatively few and far between averaging roughly 1 or 2 pros per 10 million in population.

Using the Wikipedia data, we determined the birth state of the (American born) PGA Tour Pro(s) with the most wins in each season since 1960. There were 38 unique winners (with ties) and each golfer was counted only once if they were multiple year winners. The golfers were each placed into one of seven groups by yearly average UV Index range in their birth state (<5.25; 5.25-5.74; 5.75-6.24; 6.25-6.74; 6.75-7.24; 7.25-7.74; and >=7.75). The total number of golfers in each group was divided by the total population of all states in each group.

Figure 1 illustrates the correlation (R-squared = .56) between the number of US golfers per 10 million population their birth state average UV Index. Big states such as Texas, California and Florida were divided into separate regions since the UV Index varied significantly within the state. For example the UVI in Southern California (LAX) is 7.61versus 6.31 in the San Francisco area. Population was equally divided in each region of the state. The tilt in the linear fit toward the high UV Index states is statistically significant (p = .04).

Figure 1. High UV Index States Produce Significantly More Top PGA Tour Winners.

Correlation is no proof of cause and it's impossible to tell how much of a factor (if any) sunshine and Vitamin D are in shaping a young golfer's chances of future success. Even those in the south face long odds of being a top PGA Tour pro. However, most of us would be happy enough with shaving a few strokes off our handicaps. Even with this modest goal there's no way to be sure if lessons, new equipment or other tips are making a difference. However there seems to be little downside in supplementing one's diet with more Vitamin D in the north, particularly in the winter months when the UV Index can be very low.

Table 1. PGA Tour Pros With Most Yearly Wins Since 1960.

UV Index	Birth State	PGA Tour Pro
10.00	Hawaii
9.37	Florida (MIA)
8.69	Florida (TPA)
8.39	Texas (DFW)	Brooks, Magee, Kite, Travino
8.36	Louisiana	Sutton
8.15	Alabama	Green
8.02	Florida (JAX)	Duval, McCumber
7.95	Texas (HOU)	Rogers, Crenshaw
7.90	New Mexico	Jones
7.75	Mississippi
7.75	Arizona
7.61	California (LAX)	Woods, Mickleson, Pavin, Stadler, Casper
7.44	South Carolina
7.37	Georgia
7.06	Arkansas
7.00	Nevada
6.97	Tennessee
6.88	Oklahoma	Tway, Morgan
6.70	North Carolina	Love III, Floyd
6.48	Colorado
6.41	Virginia	Strange, Wadkins
6.40	Kansas
6.40	Utah
6.31	California (SFO)	Miller, Lema
6.17	Kentucky
6.11	Missouri
6.08	West Virginia
5.88	Maryland
5.87	Delaware
5.83	Indiana	Zoeller
5.79	New Jersey	Colbert
5.67	Pennsylvania	Palmer
5.63	Idaho
5.59	Nebraska
5.53	Iowa	Purzer
5.52	New York (JFK)
5.34	Ohio	Cook, Watson, Nicklaus
5.31	Illinois
5.29	Connecticut
5.25	Rhode Island	Andrade
5.16	Michigan	Peete, Hill
5.12	South Dakota
5.11	Wisconsin
5.10	Massachusetts	Azinger
5.01	New York (BUF)	Levi
5.00	New Hampshire
4.97	Wyoming
4.97	Montana
4.85	Oregon
4.84	Maine
4.80	Minnesota	Jansen
4.76	Vermont
4.59	North Dakota
4.41	Washington	Couples
2.22	Alaska

New England Patriots’ Midwinter Blues

2008-02-02T17:03:00.000-05:00

In spite of putting together a perfect regular season, the Patriots' performance has often been questioned as their margin of victory declined. Was this just coincidental or is there a systematic trend at work that makes it difficult to maintain peak performance throughout the course of a complete football season? Dr. Michael Holik has stated that Human skin exposed to sunlight on cloudless days in Boston (42.2 degrees N) from November through February produced no previtamin D3. Could an insufficiency of Vitamin D be the cause of the Patriot's drop off from peak performance?

The pro football season starts in late summer and ends in the dead of winter, spanning a wide variation in solar intensity as measured by the Ultra Violet (UV) Index. An earlier post, Sunshine and Super Bowl XLII, noted southern teams have a bit of an edge for multiple Super Bowl wins. New York and New England are both northeastern teams and both have comparable declines in solar exposure as the season wears on. Is there a drop off in performance, as sunshine gets too weak to produce Vitamin D? More specifically, has there been any difference between the Patriots’ and Giants’ performance relative to the UV Index (UVI) over the course of the season?

The New England Patriots played their pre-season games at Tampa (UVI estimate = 11.7); versus Tennessee (7.5); at Carolina (8.8); and versus the New York Giants (6.9). The Pats started the regular season at the New York Jets (5.0) with a five-week moving average UVI of about 8.0. As the schedule unfolded in the fall, the UVI average steadily declined to 5.0 at the end of September; 4.5 at the end of October; 2.0 at the end of November; 1.5 at the end of December. Home field advantage kept the Patriots home in January and didn’t help with sun exposure.

Figure 1 summarizes the New England Patriots’ points scored, points allowed and total points over the course of the season as a function of the estimated 5 week moving average of the UV Index. A linear fit of the data is also shown to illustrate trends, though correlations are small since scores in any football game have a big standard deviation of approximately 14 points around the line. The trend lines show that the offense scored fewer points on average as the UVI declined, while the defense gave up more points. The Patriots had started the season blowing out opponents and beating the spread by a wide margin. While they ended the season unbeaten, the games were often much closer and results often fell short of Vegas’ expectations.

The New York Giants UVI also started high (7.8) and declined as expected during the fall into winter. However, the Giants had two playoff games in January that took them to Tampa Bay and Dallas where the solar intensity was much greater than what the Patriots experienced at home. The Giants’ offensive production trend (shown in Figure 2) decreased slightly as the UV Index declined. On defense the trend actually improved a bit (allowed fewer points) as a function of decreasing UVI.

Figure 2. Giants’ Offense Has Declined Slightly as UVI Declined.

With the Patriots’ 5 week moving average UVI currently at 2.0 they should win 32.4 - 18.0 over an average opponent. In contrast, the Patriots’ overall season average score was 35.6 - 17.0, Therefore based on UVI the Pats should under perform by 3.2 points on offense and 1.0 points on defense or a total of 4.2 points. As a result of the playoff games in the south, the Giants’ 5 week moving average UVI is currently 2.9. The linear fit in Figure 2 suggests they should beat an average opponent by 22.8 – 20.7. In contrast, the Giants’ overall season average score was 23.2 – 21.2. The Giants would be expected to under perform on offense by 0.4 points but make it up on defense. UVI exposure would appear to favor the Giants by nearly 4 points… not enough to offset the 12.5 point line for the game, but enough perhaps to make the game interesting.

While there isn't enough data here to draw any firm conclusions, the noticeable drop in the Pats' offensive production with declining UV Index levels suggests that Vitamin D levels could be a factor. Further research may shed light on this question but until then, Vitamin D should be monitored and supplements may be beneficial for maintaining peak performance.

Table 1. Sun Exposure Declines Substantially During the Football Season

Date	NY Giants	UVI (5 week)	NE Patriots	UVI (5 week)
Sunday, 9/9	at Dallas	7.8	at Jets	8.0
Sunday, 9/16	GREEN BAY	7.1	SAN DIEGO	6.8
Sunday, 9/23	at Washington	6.6	BUFFALO	6.5
Sunday, 9/30	PHILADELPHIA	6.2	at Cincinnati	5.0
Sunday, 10/7	NEW YORK JETS	5.9	CLEVELAND	4.5
Monday, 10/15	at Atlanta	5.4	at Dallas	4.6
Sunday, 10/21	SAN FRANCISCO	4.8	at Miami	5.1
Sunday, 10/28	at Miami (London)	4.5	WASHINGTON	4.4
Sunday, 11/4	BYE	4.1	at Indianapolis	4.6
Sunday, 11/11	DALLAS	3.7	BYE	4.2
Sunday, 11/18	at Detroit	2.9	at Buffalo	3.3
Sunday, 11/25	MINNESOTA	2.6	PHILADELPHIA	2.0
Sunday, 12/2	at Chicago	2.1	at Baltimore	1.9
Sunday, 12/9	at Philadelphia	1.9	PITTSBURGH	1.7
Sunday, 12/16	WASHINGTON	1.6	NY JETS	1.5
Sunday, 12/23	at Buffalo	1.4	MIAMI	1.6
Saturday, 12/29	NEW ENGLAND	1.3	vs NY Giants	1.5
Sunday, 1/6	at Tampa Bay	2.0	BY	1.4
Sunday, 1/13	at Dallas	2.2	JACKSONVILLE	1.4
Sunday, 1/20	at Green Bay	2.2	SAN DIEGO	1.4
Sunday, 1/27	BYE	2.4	BYE	1.5
Sunday, 2/3	NE Patriots	2.9	NY Giants	2.0

Sunshine and Star Football Recruits

2008-02-01T21:38:00.000-05:00

With letter of intent day just around the corner, college football recruiters are making their final push to land the best prospects. Top kids are rated by the star system, with 3, 4 and 5 star athletes being the most sought after. As discussed in Football's Southern Exposure, the southern latitudes produce a greater than average share of football talent on a per capita basis. The same holds true for this year's national recruiting class as rated by Rivals.

There may be many reasons for the talent advantage in the south. Football may simply be more popular in the south. Warmer weather makes for a longer period of outdoor activity and practice. Simply spending more time in the sun leads to higher Vitamin D levels which can further boost athletic performance. As suggested by Dr. Cannell: Five converging—but totally separate—lines of scientific evidence leave little doubt that vitamin D improves athletic performance. Vitamin D is a potent steroid hormone that needs to be managed. Most people don't get enough sunshine especially in the north where the sun is too weak to produce Vitamin D in the winter.

The Rivals recruiting data base rates recruits by state. It's easy enough to calculate the number of top recruits (3, 4 and 5 star) per million population in each state and compare with the average amount of sunshine in the state (Ultra Violet Index). The top states are:

State	Population (Mil)	Rivals 3,4&5*	Athletes/Million	UVI
Louisiana	4.29	38	8.86	8.36
Mississippi	2.91	25	8.59	7.75
Alabama	4.6	35	7.61	8.15
South Carolina	4.32	25	5.79	7.44
Florida	18.09	100	5.53	8.69
Hawaii	1.285	7	5.45	10
Georgia	9.36	50	5.34	7.37
Arkansas	2.81	13	4.63	7.06
Ohio	11.48	50	4.36	5.34
Texas	23.51	100	4.25	7.95
Oklahoma	3.58	15	4.19	6.88
Virginia	7.64	30	3.93	6.41
Kansas	2.76	9	3.26	6.4
Arizona	6.17	19	3.08	7.75

Figure 1 summarizes the number of 3 or more star rated recruits for all states for which Rivals rates football prospects. Figure 2 summarizes the number of 4 and 5 star recruits by state.

Figure 1. Correlation of Rivals 3, 4 and 5 Star Football Prospects with the UV Index.

Figure 2. Correlation of Rivals 4 and 5 Star Football Prospects with the UV Index.

The correlations evident in Figures 1 and 2 are quite significant. While it is well known that recruiting the south is important, if Vitamin D is a significant reason for the prolific production of top quality athletes, then those in the north should be able to enhance their prospects by better managing their Vitamin D intake.

So the most important star in the recruiting game may be the one most of us don't get enough of (at least in the northern latitudes). The UV Index is a measure of the potential for Vitamin D production. Vitamin D is a potent steroid hormone that is vital for good health and developing to one's fullest potential. While southern athletes have a natural advantage due to greater sun intensity, northern athletes can level the playing field by means of diet and supplements.

Sunshine and Super Bowl XLII

2008-01-26T18:36:00.000-05:00

When it comes to peak athletic performance, it doesn’t get much better than the Super Bowl. Table 1 lists the 21 (of 32) NFL teams that have at least one win or two appearances in past Super Bowls. New England and New York are both among the top teams. The Patriots are now tied for second with 6 total Super Bowl appearances while the Giants move up to a tie for fourth with 4 appearances.

We’ve seen in an earlier post Football’s Southern Exposure that the sunny southern states produce more quality college football players per capita than the dimmer northern states. But the pros can draft the best talent and level the playing field. So one might wonder if there is any additional benefit from normal sunlight exposure for NFL teams.

Figure 1 summarizes the number of Super Bowl appearances as a function of each team’s potential sunshine exposure. The straight line fit to the data has a positive tilt as the UV Index goes up. Wins follow a similar pattern with a slightly better positive correlation (R-squared = 0.05). Even a small correlation is worth noting in a game where a slight edge can make a difference in the outcome of a game. All else being equal, the correlation would vanish if a low UVI team had 4 more wins at the expense of a high UVI team, e.g. if the Jets had 5 wins instead of 1 and Dallas had 1 win instead of 5. A swing of four Super Bowl wins out of 41 played is roughly a 10% factor.

It's quite possible that the four game tilt favoring sunnier NFL teams is just due to luck. Or it may be that the sunshine factor, Vitamin D, is essential for peak athletic performance. Northern teams' Vitamin D levels may drop more than southern teams. In the winter months UV Levels in northern cities such as New York and Boston fall substantially below the point where the sun can produce Vitamin D in the skin.

However, there is no magic bullet here for handicapping the outcome of Super Bowl XLII as the difference in UV Index between New York and Boston isn't much of a factor. While the Giants may have benefited from recent road games in Tampa and Dallas, both teams will have a chance to catch some rays in the Arizona sunshine prior to the big game.

Figure 1. NFL Super Bowl Appearances are
Positively Correlated with UV Index

Most of the credit for Super Bowl wins has traditionally gone to the quarterbacks. Multiple-win quarterbacks have become near legendary in status. Here’s a summary of multiple Super Bowl winning QBs, and their birth states:

Pittsburgh Steelers: Terry Bradshaw, Louisiana – 4 wins
San Francisco; Joe Montana, Pennsylvania – 3 wins
Dallas Cowboys: Troy Aikman, Southern California – 3 wins
New England: Tom Brady, California (SF Bay area) – 3 wins
Denver Broncos: John Elway, Washington – 2 wins
Miami Dolphins: Bob Griese, Indiana – 2 wins
Oakland/LA Raiders: Jim Plunkett, California (SF Bay area) – 2 wins
Green Bay Packers: Bart Star, Alabama – 2 wins
Dallas Cowboys: Roger Staubach, Ohio – 2 wins

Does the sunshine factor come into play with these elite athletes? There is in fact a tilt or correlation between the number of Super Bowl wins and increased exposure to Ultra Violet light in the quarterbacks’ original home states. While there isn’t enough data here to be statistically significant, there’s no need to wait several more decades for absolute proof. Managing Vitamin D through sun exposure, diet or supplements is prudent based on the overwhelming evidence of reduced risk of chronic diseases even if it won’t make you a superstar athlete. But if you happen to be Eli Manning, well maybe you can become the next legend.

Figure 2. NFL Quarterbacks’ Super Bowl Wins are
Correlated With Birth State UV Index

Table 1: NFL Super Bowl Record
(Teams with at least one win or two appearances)

Team	Wins	Losses	Days/Year UVI>6
Dallas Cowboys	5	3	183
Pittsburgh Steelers	5	1	113
New England Patriots	3	2	102
Denver Broncos	2	4	162
San Francisco 49ers	5	0	156
Oakland Raiders	3	2	156
Washington Redskins	3	2	131
Miami Dolphins	2	3	262
Green Bay Packers	3	1	101
New York Giants	2	1	103
Buffalo Bills	0	4	97
Minnesota Vikings	0	4	94
Indianapolis Colts	2	1	111
St. Louis Rams	1	2	125
Chicago Bears	1	1	105
Kansas City Chiefs	1	1	136
Cincinnati Bengals	0	2	101
Philadelphia Eagles	0	2	114
Baltimore Ravens	1	0	129
New York Jets	1	0	103
Tampa Bay Buccaneers	1	0	239

Super Bowl XLII: Rating the D

2008-01-24T21:39:00.000-05:00

Green Bay had the home field advantage. But was it really an advantage? The Packers hadn’t ventured further south than St. Louis since playing at Dallas on November 29. That’s 8 weeks without much sun prior to playing the Giants. In fact, after starting 10 and 1, the Packers went just 4 and 3 to end the season. In contrast, the Giants were doping up, err… soaking up sunshine in balmy Tampa Bay on January 6 and again the following week in Dallas, giving them a clear edge on D going in to the NFC championship game, Vitamin D that is.

The Patriots have also enjoyed their home field advantage in the playoffs, but they haven’t been south of Baltimore in the past two months. While the Pats are still undefeated they haven’t beaten the spread in their last four games. Now they face the Giants as a 12.5 point favorite in Glendale, Arizona. The Giants may still have an edge on D, but New England also has a chance to recharge their supplies of this natural steroid hormone. Perhaps the Giants would have been better off if the game were being played in New England.

Stanley Cup Thawing Out

2008-01-21T16:16:00.000-05:00

For a time, the NHL expansion provided cannon fodder for the established original six hockey programs. However, times are changing. The most recent winners include: 2006-07 Anaheim Ducks; 2005-06 Carolina Hurricanes; 2003-04 Tampa Bay Lightning. The Colorado Avalanche and Dallas Stars have also been winners in the past 10 years.

Is southern hockey excellence just a chance development? Perhaps it’s too soon to tell. Perhaps transplanting top hockey talent from the frozen north to the sunnier south gives these athletes a competitive advantage. Hockey players from the northern latitudes may spend more time indoors, and be more likely to have a Vitamin D deficiency than their southern counterparts. According to Dr. John Cannell of the Vitamin D Council:

If you are vitamin D deficient, the medical literature indicates that the right amount of vitamin D will make you faster, stronger, improve your balance and timing, etc. How much it will improve your athletic ability depends on how deficient you are to begin with. How good an athlete you will be depends on your innate ability, training, and dedication.

Figure 1 summarizes the average UV Index of the cities comprising the National Hockey League. As the NHL expanded primarily into the southeast and southwest, the average UV Index of the league also increased gradually. Figure 1 also shows the UV Index of the teams that won the Stanley Cup along with a 10-year moving average. Figure 1 shows that the 10-year moving average of the UV Index for the Stanley Cup winners has been increasing at a faster pace than the increase in UV Index for the league as a whole.

Figure 1. Stanley Cup Winner and NHL Average UV Index.

Athletes and other individuals should consider being tested for Vitamin D to determine whether or not they are below optimal levels. While those who live in the south have the benefit of sunshine, northerners can take advantage of diet and supplements.

Football's Southern Exposure

2008-01-17T20:10:00.000-05:00

PJR1 and RUbytheshore

Introduction.

Look at where many of the best football players in the country come from: California, Texas, and Florida. Those three, by far, are the best states at producing football players for college football on the Division 1-A level in both quantity and quality. This also holds true for producing football players in the National Football League. Not only are these three states the best at producing players for the collegiate level, they’re well ahead of the fourth and fifth best states, Ohio and Georgia.

Many will ask why this is so. Several factors weigh into this. Population is one. In addition, the level of interest and increased practice time, such as having spring football, are also important. One common thread these three states have is a warmer climate.

A warmer climate allows kids to play outdoors more often than kids in a cooler climate. When kids are outdoors more often, they participate in recreational activities, including athletics. They’re more likely to be outdoors twelve months a year than many other states. The other states may have as many as six months where kids are more likely to stay inside.

Being outdoors more often in a warmer climate can allow athletic skills to develop more rapidly than being in a colder climate where kids aren’t as likely to be competing outdoors as often. Being outdoors also exposes kids to the Vitamin D producing sunshine which is a potent source of natural steroid hormones that may boost athletic performance.

Which States Produce the Most Division 1A Football Players?

Rutgers Rivals football message board poster, PJR1, checked the current rosters of all 117 Division 1A football teams to evaluate which states produce the most football players. The results show that the big southern states of California, Texas and Florida are well above average in terms of sheer numbers, each having produced well over 1200 players per state, The mid-west is also well represented in the top 10, including Ohio with 690, Pennsylvania with 374, Illinois with 343 and Michigan at 338. New Jersey comes in 13th with 241 players while New York is in the top 20 with 167 players.

Some of the mid-west’s relatively large showing may be due to the popularity of the Big 10 Conference and a second regional Mid America Conference (MAC) which is centered in the mid-west. In contrast, the east has fewer 1A programs and eastern athletes may be more likely to wind up in Division 1AA schools and therefore excluded from our count. The count does not differentiate between scholarship athletes and “walk-on” athletes, nor does it distinguish between the skill levels of the players on individual team rosters (e.g. starters, backups and practice squad).

The ranking changes somewhat when normalized by the number of Division 1A athletes per million residents in each state. This gives equal weight to geographically smaller and less populated states. On a per capita basis, Hawaii comes in first by wide margin with 104 athletes per million. Louisiana moves to second place and Florida slips to third while California drops all the way to 15th place.

At the other end of the spectrum, the northern and northeastern states produce the fewest Division 1A football players with Vermont and North Dakota having each contributed no athletes to the rosters of major football programs. Perhaps the athletes in these particular northern states are more interested in hockey and lacrosse. New York, Massachusetts and Connecticut also produce relatively few top football players on a population adjusted basis even though they have extensive high school football programs.

Sunshine and Vitamin D.

According to Dr. John Cannell (1) of the Vitamin D Council, most people are deficient in Vitamin D. Since the Industrial Age began, we have had a tendency to live and work indoors, and more recently have been encouraged by the medical authorities to avoid the sun for fear of skin damage, cataracts and even skin cancer. However, by avoiding the sun we decrease the production of Vitamin D which is primarily produced in the skin when it is exposed to the ultra violet rays in sunshine.

Vitamin D has been shown to be vital to good health and chronic deficiencies have been linked to poor bone health and higher risk for major diseases such as cancer, multiple sclerosis, diabetes and depression. For athletes, Vitamin D is thought to affect athletic performance primarily because it plays a key role in the body’s production of a very potent steroid hormone, calcitriol. As Dr. Cannell suggests:

... peak athletic performance also depends upon the neuromuscular cells in your body and brain having unfettered access to the steroid hormone, activated vitamin D. How much activated vitamin D is available to your brain, muscle, and nerves depends on the amount of 25-hydroxyvitamin D in your blood. In turn, how much 25-hydroxyvitamin D is in your blood depends on how much vitamin D you put in your mouth or how often you expose your skin to UVB light.

Florida, Texas and California, well known as fertile recruiting grounds for major college football programs, are sunny states. Hawaii has an extremely warm and sunny climate. If Vitamin D is a key factor in the production of top tier football players, there should be a correlation between the number of athletes on Division 1A football teams and the levels of Vitamin D producing Ultra Violet (UV) radiation in the states where they come from.

The UV Index (2) is a forecast of the amount of UV radiation expected to reach the earth's surface at the time when the sun is highest in the sky (solar noon). The amount of UV radiation reaching the surface is primarily related to the elevation of the sun in the sky, the amount of ozone in the stratosphere, and the amount of clouds present. The UV Index can range from 0 at night time to 12 or 13 (in Miami or Hawaii under clear skies). Tropical areas with high altitude can have even greater UV Index predictions, though those areas do not occur in the United States. We use the UV Index as a measure of the potential for sun exposure and Vitamin D production. For example, Table 1 summarizes the number of days the UV Index Forecasts in 2006 fell into a certain range for Honolulu, Hawaii and Burlington, Vermont at opposite extremes of the sunshine intensity spectrum.

UV Index Range	Honolulu, Hawaii (Days per Year)	Burlington, Vermont (Days per Year)
Extreme > 11	115	0
Very High 8-11	115	19
High 6-8	91	52
Moderate 3-6	30	76
Low < 3	6	210

Table 1: UV Index Range for Hawaii and Vermont (Days per Year).

Correlation of the UV Index with D1A Football Players per Capita

Table 2 presents the data for three cases of the UV Index within each state: a) Low (< 3); b) Moderate (3-6); and c) High to Extreme (> 6). We find a substantial correlation (R-squared = 0.56 in Figure 1) between the number of Division 1A football players and days per year having High to Extreme UV Index within the state. We also find a substantial negative correlation (R-squared = 0.49 in Figure 2) between the number of Division 1A football players and days per year having Low UV Index. Between these extremes the number of Division 1A football players is not correlated (R-squared = 0.0017) with days per year having Moderate UV Index.

Figure 1. Positive Correlation: Div !A Football Players with High UV Index.

Figure 2. Negative Correlation: Div !A Football Players with Low UV Index.

We also find a correlation of the Rivals Recruit Data Base (3) by state with the UV Index. Specifically we determined the number of 3, 4 and 5 star rated recruits per million population within a state and correlate this with the number of days per year with UV Index levels in a particular range. The new recruits represent new prospective players who are currently seniors in high school. We find a positive correlation (R-squared = 0.52) of the number of highly rated recruits by state per million capita with the number of days per year with UV Index rated higher than 8. We also find a negative correlation (R-squared = 0.50) of number of athletes per million with number of low (< 3) UV Index days per year.

Conclusion.

Southern states do produce more top tier football players per capita than northern states. The reasons for this appear to include greater opportunity to practice outdoors in spring as well as fall. Greater opportunity for being outdoors also enables greater sun exposure and Vitamin D production. The number of 1A quality level football players produced from each state is positively correlated with the number of days per year with high UV Index (greater than 6) and associated high levels of Vitamin D production. The number of athletes is negatively correlated with number of days per year with low UV Index (less than 3). While this correlation could be due to a variety of factors, it supports Dr. Cannell's view that Vitamin D levels may be a significant factor in athletic performance.

The potential benefits of sunlight and Vitamin D for athletic performance suggests that individuals should consider being tested for Vitamin D to determine whether or not they are below optimal levels. Vitamin D levels can also be boosted either with diet or supplements. For example, oily fish such as wild Alaskan salmon is a good source of natural Vitamin D. However, care should be exercised with supplements. As Dr. Cannell advises:

A word of caution, though.. studies suggest that taking too much vitamin D (more than 5,000 IU/day) may actually worsen athletic performance. So take the right amount, not all you can swallow. Take enough to keep your 25_hydroxyvitamin D levels around 50 ng/mL, year_round. Easier yet, regularly use the sun in the summer and a sunbed (once a week should be about right) in the winter—with care not to burn.

References.

1. Dr. John A. Cannell, “Peak Athletic Performance and Vitamin D” The Vitamin D Newsletter, March 2007
2. National Weather Service, Climate Prediction Center
3. Rivals Recruiting Data Base

State (City UV Index)	# Div 1A Football Players	per Million	UVI < 3 (Days/Year)	3 < UVI < 6 (Days/Year)	UVI > 6 (Days/Year)
1. Hawaii (Honolulu)	133	104	6	30	321
2. Louisiana (New Orleans)	358	83	44	97	216
3. Florida (Tampa)	1212	66	19	99	239
4. Ohio (Cleveland)	690	60	172	84	101
5. Alabama (Mobile)	275	59	46	104	207
6. Georgia (Atlanta)	511	54	85	99	173
7. Mississippi (Jackson))	152	52	61	104	192
8. Texas (Dallas)	1226	51	76	98	183
9. Nebraska (Omaha)	87	49	151	90	116
10. Wyoming (Cheyenne)	25	48	113	95	149
11. Kansas (Wichita)	118	43	127	94	136
12. Arkansas (Little Rock)	120	42	109	75	173
13. Colorado (Denver)	194	40	104	91	162
14. Nevada (Las Vegas)	102	40	69	112	176
15. California (Los Angeles)	1380	38	43	123	191
16. Iowa (De Moines)	112	37	159	87	111
17. Oklahoma (Oklahoma City)	132	36	103	84	170
18. Utah (Salt Lake City)	96	36	111	88	158
19. Michigan (Detroit)	338	34	185	74	98
20. South Carolina (Charleston)	147	33	67	106	184
21. Virginia (Norfolk)	247	32	123	90	144
22. New Mexico (Albuquerque)	60	30	43	104	210
23. Pennsylvania (Pittsburgh)	374	30	173	71	113
24. Indiana (Indianapolis)	190	30	158	88	111
25. Tennessee (Memphis)	174	28	120	85	152
26. North Carolina (Raleigh)	254	28	114	91	152
27. New Jersey (Atlantic City)	241	28	149	90	118
28. Washington (Seattle)	179	28	182	86	89
29. Idaho (Boise)	41	27	131	95	131
30. Maryland (Baltimore)	151	27	147	81	129
31. Illinois (Chicago)	343	27	169	83	105
32. Missouri (St. Louis)	148	25	145	87	125
33. Kentucky (Louisville)	106	25	149	86	122
34. Arizona (Pheonix)	158	25	38	114	205
35. Oregon (Portland)	84	22	185	63	109
36. Alaska (Anchorage)	13	19	266	91	0
37. Wisconsin (Milwaukee)	103	18	167	89	101
38. Minnesota (Minneapolis)	95	18	176	87	94
39. Connecticut (Hartford)	60	17	182	80	95
40. West Virginia (Charleston)	25	14	161	86	110
41. Delaware (Dover)	8	9	152	85	120
42. Massachusetts (Boston)	58	9	167	88	102
43. New York (New York)	167	9	158	96	103
44. Montana (Billings)	6	6	150	83	124
45. South Dakota (Sioux Falls)	4	5	169	78	110
46. Rhode Island (Providence)	5	5	179	78	100
47. New Hampshire (Concord)	5	4	182	86	89
48. Maine (Portland)	1	1	179	92	86
49. North Dakota (Bismark)	0	0	176	86	95
50. Vermont (Burlington)	0	0	210	76	71

Table 2: Division 1A Football Players Per State.