Masters Athlete

Fluid Loss in Masters Swimmers – Effects of Water Temperature

January 17th, 2012

Introduction

Most experienced and competitive masters swimmers have trained or competed in many different pools, lakes, rivers and oceans, and under many different climatic conditions and water temperatures. We’ve learnt that hard sessions in warm water can work up a thirst. While little research has been done on fluid loss in swimmers, here is some recent Italian research that used older open water swimmers as their subjects. The results suggests the level of dehydration, the sweat rate, and the body temperature all increase with increased water temperature as we move from cool to warmer water.

The Research

The purpose of the study was to evaluate the effects of three different water temperatures (23, 27 and 32 ̊C) on physiological responses (dehydration, sweat rate, urine output, rectal temperature, plasma electrolytes and fluid balance) to a “simulated” race of 5 km in competitive athletes in an indoor 25m pool. Nine competitive male master swimmers ranked in the top 5 of category in open water (1.5–10 km) Italian races, were studied (age: 34.6 ± 14.4 years, height: 172.1 ± 9.8 cm, mass: 72.7 ± 8.5 kg, body fat: 12.7 ± 3.5%). The subjects trained five to six times per week (3–8 km per training session) in 25- and 50-meter swimming pools (water temperature about 27 ̊C). Each swimmer completed three experimental trials, separated by 7 days, in a 25-meter indoor swimming pool; they swam 5 km with water at the temperatures of 23, 27 and 32 ̊C. The swimming speed of all athletes in each trial was as close as possible to their personal lactate threshold speed (race pace). No food or fluid was used during the tests. The sport scientists measured body weight, rectal temperature, urine output, and blood electrolytes (sodium, potassium and magnesium before and after each swim.

The Results

Sweat rate increased and body weight loss (%) decreased with increased water temperature (Table 1).

Urine output after each swim was no different between the trails. Body temperature only increased in the 27 and 32 ̊C trials. The sodium level in the blood only increased in the 32 ̊C swim and most probably due to the amount of fluid lost. The researchers concluded that dehydration, sweat rate and body temperatures simultaneously increase with the rise of water temperature during the shortest open water swimming event distance (5 km) performed at race intensity.

So What?

This unique study confirms that as water temperature increases we need to be more cautious about ensuring our hydration status is good. Drink fluids before a pool session and ensure, particularly in hard sessions in warmer water (its 31 ̊C in our Uni pool at present!), that you replace fluids regularly during your session. The hotter the water, the more fluids you need to drink. The harder and longer the session, the more fluids you need to drink. If you are a once a day swimmer doing sessions under an hour, water is all you need. Twice a day and/or doing sessions longer than an hour and/or hard, the more important sports drinks become. For more on temperature regulation and fluid guidelines for masters athletes, see Chapter 11 of my book The Masters Athlete – Exercising in the Heat and Cold.

Source: Macaluso et al. (2011) Effects of three different water temperatures on dehydration in competitive swimmers. Science in Sports, 26: 265-271.

Browse related items: fluids, swimming

Shoes for Breasts: What Research Says About Sports Bras

November 28th, 2011

Introduction

Little research has been done in this area. This is unusual given that approximately one third of female athletes complain of breast discomfort when exercising and as little as 2 cm of breast displacement can cause breast discomfort. One of the leading researchers focusing on sports bras is Professor Julie Steele from the University of Wollongong in Australia. Julie, together with Sport Physiotherapist Dr Diedre McGhee, recently summarised the research done to date on sports bras and what to look for in sports bras.

The Facts

Breasts are supported by the overlying skin and a series of small ligaments throughout the breast tissue. However, these can’t limit breast movement through exercise. In fact, research has shown that unsupported breasts can move as much as 12cm during running. This movement can be reduced by up to 50% by wearing a well-supported sports bra. Julie’s research team has shown that only 41% of adult women exercisers wore a sports bra and 80% of adolescent females had inadequate breast support relative to their bra size and sport they were involved in. This poor level of support has been shown to lead to self-consciousness in adolesecnt athletes and a major barrier to larger breasted women actually exercising. In large breasted women it is common to have the arms braced against their trunk to limit breast movement. This changes run technique and inhibits actual performance.

Features of a High Support Bra

Three types of bra are available – the sports bra that limits breast movement by encapsulating each breast, the crop top that flattens the breasts as a single unit against the chest, and the fashion bra that is designed for appearance, not as a limit to breast movement. For light activity for a small-breasted woman, crop tops may do the trick. However, for a large breasted woman running hard, a sports bra and crop top may be the best suggestion to limit breast movement. Below are the features our sport scientists suggest to look for when selecting a sports bra:

1. Cups should completely cover the breasts using supportive material – not lace or lycra. The cups should have no wrinkles or gaps (too big) and no buldging breast tissue over the top or sides of the cup (too small).
2. Band should be made of strong elastic material and be wide enough relative to breast size: A cup – 1 clip; B/C cup – 2 clips; D+ – 3 clips wide. The band should not ride up when moving the arms above the head (too big) and no flesh buldging over the top edge of the band (too small).
3. Straps must be wide and comfortable. Straps should not slide off (too big) and not dig in (too small).
4. Front bands should sit flat against the breastbone.
5. Underwire or soft-cup? An underwire should not sit on any breast tissue. If it doesn’t sit on the ribs or breastbone, a soft-cup bra is the best option. If it sits on breast tissue, the bra is too small.

More Reading?

If you want to read more, Sports Medicine Australia will soon have a great fact sheet for female exercisers. Our book The Masters Athlete has the most definitive (biased as I am not!) chapter (number 19) available on what sport and exercise science has found out about female masters athletes. Discussed in detail are the effect of the menstrual cycle on performance, menstrual irregularities, coping with menopause as an athlete, hormone replacement therapy, training through pregnancy, nutritional concerns of older female athletes, and ways of coping with PMT. A great Xmas present for a friend or spouse.

Source: McGhee, D. & Steele, J. (2011). Are breasts a problem for women in sport? Sport Health, 29(3): 42-47.

Browse related items: females, women

Why do older sprinters get slower?

November 16th, 2011

The Introduction

The purpose of this review was to identify the major factors leading to declines in sprint (run) speed in track athletes. The German-based research describes the factors that affect age-associated changes, including reduction of training overload, reduction of maximum force, and change in body composition (mainly a decrease in muscle mass due primarily to a reduction in fast twitch muscle fibre size) associated with aging. The three major factors the research suggests are responsible for a decrease in sprint speed in older track athletes are: the lower maximum strength of the lower limb muscles, the slower rate of force development and force transmission to the ground, and reduction in the elastic energy storage and recovery in tendons.

The Research

The researchers reviewed 34 papers that have examined the effects of aging on the speed of muscle contractions and tendon elasticity in both rats and humans including non-athletes, endurance and sprint runners.

The Results

They concluded that aging sprint runners preserve their stride frequency but appear to reduce their stride length as they age. Moreover, this reduced stride length appears due to reduced propulsive ground reaction forces and the rate of development of this force. That is, the ability to push off the ground quickly is reduced. This reduction appears mainly due to three major factors:

1. Lower maximal strength of the lower limb muscles (about 30% from young to old) due to reduced size of the fast twitch muscle fibres;
2. The slower rate of force development and transmission of this force to the ground; and,
3. Reductions (about 35% from young to old) in elastic energy storage and energy recovery in tendons due to reduced tendon stiffness in older athletes.

The So What?

The news isn’t good is it? However, while declines in all these factors appear inevitable in older sprinters, we can reduce the rate of decline in a number of ways. First, ensure hypertrophy (muscle enlargement) resistance training becomes part of a sprinters training regime, especially in the off and pre-season. This will help build or at least maintain muscle mass. Specific details (exercises, sets, reps, loads etc) on how this is done are found in chapter 7 of my book The Masters Athlete. Second, power training including pliometrics (bounds, hops, and jumps) and gym work (e.g. jump squats) is included in all training programs. This type of training develops the rate of force development and elastic energy stored in tendons and the tissue surrounding muscle fibres. Specific details on pliometrics (examples, principles, suggested repetitions) are found in chapter 8 of my book The Masters Athlete. Finally, flexibility training is crucial for all masters athletes, especially sprinters whose stride length decreases with age. Again, chapter 9 of my book The Masters Athlete discusses in detail the principles and how to’s of flexibility training.

Arampatzis, A., Degens, H., Baltzopoulos, V. and Rittweger, J. (2011). Why Do Older Sprinters Reach the Finish Line Later? Exercise & Sport Sciences Reviews. 39(1): 18 – 22.

Photo Source: http://www.masterstrack.com/gallery/main.php?g2_itemId=45390&g2_imageViewsIndex=1

Browse related items: running speed, sprinting, training principles

Does dehydration decrease performance? Maybe not!

November 15th, 2011

Introduction

There has been some robust debate recently in the sport science literature. Some experts are saying a level of dehydration is safe in endurance athletes and that we should rely on thirst to tell us when to drink. In contrast, there are some experts that say drink before we get thirsty and try and maintain your body weight during endurance exercise. This research study on marathon runners suggests marathon performance is better in those that lose more body weight.

The Research

Body weight changes were measured in 643 marathon finishers (560 males and 83 females) before and after the 2009 Mont Saint-Michel Marathon in France.  The runner’s body weight was measured 60-90 minutes before the start of the marathon while they were wearing their running clothing but not shoes. Within 20m of the finish of the event their body weight was measured again by the same researcher on the same scales. Again, no shoes and the same clothing were worn and yep, some sweat may have been in the clothes! Runners were advised to drink 250 mL of fluid (sports drink or water) every 20 minutes during the event. Weather conditions were: 9-16 degrees Celsius, 60-82% humidity and strong winds. For statistical analysis, the runners were divided into three groups – sub 3hr, 3-4 hr, and greater than 4 hour marathoners.

The Results

The average age of the runners was 43±8.8 years and runners lost on average 1.7 kg or 2.3±2.2% of their body weight during the event. Males and females lost similar amounts of fluid (1 kg weight loss equals approximately 1 litre of fluid loss) and their was no effect of age on fluid loss. The weight lost ranging between gaining 5% and losing 8% of pre-race body weight. 55% of runners lost more than 2% of their body weight - the gold standard often mentioned as leading to decreased endurance performance.

Interestingly, and here is the punch line for this research, the runners who finished under 3 hours lost significantly more body weight (3.1±1.9%) and thus fluids than either the 3-4 hr runners (2.5±2.1%) and the 4 hr plus runners (1.8±2.4%). When the scientists plotted the relationship between race time and body weight lost, the relationship was very strong suggesting the greater the weight lost, the faster the run time.

So What?

The bottom line is that these results support a growing body of evidence that questions the laboratory-based findings that a body weight loss of greater than 2% impairs sport performance. In contrast, the results support previous field-based studies that show that successful athletes in marathons, ultra-distance, and triathlon events are those who lose more than 3-4% of body weight during competition. The other intersting observation from this study was that almost 10% of runners gained weight by overdrinking, an observation common in ‘back of the packers’ who read they should drink a lot but often aren’t exercising as hard as faster runners and thus may not lose fluids as much as the books suggest. This overdrinking can lead to potentially fatal condition called hyponatremia (low blood salt levels).

The bottom line again, drink before, during and after training and events and monitor your body by listening to how it responds. For information on the effect of heat (and cold) on masters athletes and, more importantly, how to manage exercising in the heat and cold as an older athlete, see Chapter 11 of my book The Masters Athlete.

Browse related items: endurance performance, fluids, weight loss

Chocolate Milk for Recovery? – I Like That Idea!

October 17th, 2011

Introduction

There has been a lot written about the importance of recovery nutrition in athletes young and old. Historically, it was all about taking in high glycemic index food or fluids within 30 minutes of finishing training or racing. Then sport science found that adding protein in a 4:1 carbohydrate to protein ratio enhanced recovery and muscle repair. Big business jumped in and developed new products to make it easier for athletes to enhance their recovery and make it easier to back up for training or racing the next day or even the same day. Now some recent recent research is suggesting commercially-available flavoured milk might just do the trick.

The Research

After determing their cycling VO2max and 40 k cycling time trial performance, ten (5 male, 5 female) trained cyclists and triathletes aged 18-39 years visited the lab on three separate occasions  after an overnight fast. On each of the three visist they cycled at 70% of their VO2max for 90 minutes (hard work) then 10  minutes of alternating one-minute  intervals at 40% of VO2max then 90% of VO2max. This protocol was designed to deplete their muscle glycogen (carbohydrate) stores. They then recovered in the lab for 4 hrs and received one of three treatments immediately after the glycogen-depleting bike ride and then again 2 hrs into the 4 hr recovery.  Muscle biopsies were taken immediately after the glycogen depleting ride and at 45 and 240 minutes into recovery. The three types of recovery drinks (see table below) were a commercially-available chocolate milk, a carbohydrate drink matched for energy content, and a placebo drink made up of some artifical sweetener and flavouring.

Table 1: Energy and composition of recovery drinks (per 100 mL)

They then did a 40k time trial on the bike to see which recovery drink improved 40k time trial performance the best.

The Results

The 40 k time trial was faster after using the chocolate milk recovery drink (79.4±2.1 min) than the carbohydrate (85.7±3.4 min) or placebo (86.9±3.3 min) drinks. Muscle carbohydrate (glycogen) resynthesis after the four hour recovery was higher in both the chocolate milk and carbohydrate compared to the placebo condition but not different between the two carbohydrate drinks. Crucially, the cholcolate milk containing the protein and carbohydrate increased protein synthesis markers (suggesting muscle recovery) to higher levels than both the carbohydrate and placebo drinks at 45 minutes into recovery.

So What?

The results of this study strongly suggest that taking a carbohydrate-protein drink after hard training or racing can improve subsequent performance and provide a greater stimulus for muscle repair and adaptation compared to carbohydrate drinks alone or plain water. This is why I use products such as Accelerade or PureSport after hard training or racing. They work, particularly when combined with all the other recovery strategies discussed in detail in Chapter 15 of  my book The Masters Athlete.

Source: Ferguson-Stegall, L. and others (2011). Postexercise carbohydrate-protein supplementation improves subsequent exercise performance and intracellular signaling for protein synthesis. Journal of Strength and Conditioning Research, 25(5): 1210-1224.

Browse related items: nutrition, recovery, supplements