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Take-home Message: This article supports the idea that taking an iron supplement can improve the athletic performance of women who are iron-deficient.

     Women of reproductive age are at a high risk of iron deficiency due to menstruation. In female athletes, the risk is even higher due to factors such as low-iron diets and low levels of inflammation caused by endurance exercise. When severe enough, iron deficiency can lead to anemia (low concentrations of hemoglobin in the blood). Hemoglobin is the protein in your blood that carries oxygen to the rest of your body, including your muscles during physical exertion. Oxygen is important for muscles because it is used during aerobic (literally meaning, “with oxygen”) metabolism, which produces the energy required for your muscles to contract. A key component of hemoglobin is iron; therefore, if you are deficient in iron, your blood cannot carry as much oxygen and your physical performance may suffer.

     At least, that has been the theory of exercise scientists. Until now, however, there have been few studies that have demonstrated this relationship clearly. This article in the Journal of Nutrition, however, is a meta-analysis of 22 smaller studies.  That means that it pooled the data from smaller clinical trials. This procedure can be useful because the larger the number of patients included, the more power you have to detect a small difference between experimental and control groups.

     When data from the smaller studies were pooled, the researchers found that an oral iron supplement improved both maximal and submaximal exercise performance in the women participants. Maximal, or peak, exercise performance was measured by VO2 max, which is the highest rate at which your body can consume oxygen. Everyone has a different VO2 max, which is influenced by things like genetics and training. Imagine running on a treadmill at a sprint until you reach exhaustion – by the end, you’ll be using oxygen as fast as your body possibly can and you’ll be at your VO2 max. In general, the higher your VO2 max, the longer you can run on that treadmill before you become exhausted. The VO2 max of women given iron supplements was on average higher than that of women not on supplements, suggesting that iron improved their maximal, or peak, performance. The amount that VO2 max increased by is about the same amount that training can improve your VO2 max by, which is a fairly substantial effect. At submaximal exercise (meaning exercise at an intensity that is not going to exhaust you), iron supplementation also lowered the heart rate of the women, suggesting that they were performing better at lower intensities as well.

     Importantly, these effects were mainly seen only in women known to be iron-deficient or trained athletes (who are at a greater risk for iron deficiency). So this doesn’t mean that every woman should start taking an iron supplement. It does mean, however, that if you are a woman of reproductive age, and especially if you are an athlete, it might be a good idea to talk to your doctor about checking your iron levels. If you are found to be iron deficient, an iron supplement might very well improve your athletic performance significantly.

As the weather warms (and it IS warming up, despite this morning's dusting of snow!), we will all be heading back outside for our favorite outdoor activities, and one of my new loves in the last couple years is running. It's a great chance to enjoy the beauty of the great outdoors while being active. 

Since I started running a couple years ago, I became interested in the science of running and whether there was any research that could help me improve. And, as it turns out, there is a clear relationship between running and one of my other favorite activities: maximal strength training.

Runners often strength train with lighter weights and higher numbers of repetitions, thinking that this will aid their endurance. Maximal strength training, on the other hand, refers to lifting with heavy weights and low-repetition sets. This type of strength training is thought to build strength largely through neural adaptations, meaning that your muscles, nerves, and brain are learning how to work together more effectively. I enjoy it because I often see fairly rapid progress in my strength gains and because I find it emotionally easier to push through 4 heavy reps than 12 lighter reps. :) 

There have been several studies to demonstrate an improvement in running economy (or how much energy it takes to run a given distance) following several weeks of maximal strength training. In one such study, runners were given a pre-training running test and then half of them engaged in 8 weeks of strength training involving half-squats with a heavy load. After the 8 weeks, the runners were tested again. Runners who had participated in the strength training regimen saw a 5% improvement in running economy, as well as a whopping 21% improvement in how long they could run at maximal speed compared to the control group. You can find a PDF of the original study here.

So whether you are new to running or you want to push yourself to new limits, consider adding in some maximal strength training to your schedule this spring to complement your running or walking routine. Happy running!

fat
noun - any of several substances forming the chief part of adipose tissue of animals and also occurring in plants, that when pure are colorless, odorless, and tasteless and are either solid or liquid esters of glycerol with fatty acids
adjective - corpulent; obese

I hate the word “fat”. I hate it because I am a scientist and a personal trainer and the word “fat” has two very different meanings in those two different contexts. I hate it because of the fear and shame and social stigma that have become associated with the adjective “fat”. I wish I could remove the adjective version from the English language altogether, or replace the noun with a totally new and different word. There is so much confusion and misunderstanding about the noun because of most people’s negative association with the adjective. Today I hope to change that a little with this post.

First, take a second to re-read the noun form of fat above and notice that there is no negative connotation there. This is important: Fat is not a bad word. It is a compound in your body that is necessary for absorbing certain vitamins, and when consumed, it is the source of essential fatty acids, a dietary requirement. It helps you maintain healthy skin and hair, it insulates your body organs from shock, and it helps maintain your body temperature. It can even act as a buffer against diseases, storing chemical or biological toxins until they can be removed from the body. Finally, it stores energy that can later be broken down and used by your body to do things like this:

I recently watched a moving TED talk by Lizzie Velasquez, an amazing woman who has a genetic disorder that has left her with dangerously low body fat. If you have a few minutes, it is a worth a watch for many reasons, and you will hopefully gain a greater appreciation for the good, positive things that fat does for your body.

Let’s delve a little deeper into what fat is. Fat is a compound that stores energy. In your body, fat is stored in specialized fat cells. There are two main types of fat cells: white fat cells and brown fat cells. White fat cells are the ones you probably think about when you think of body fat: they store fat for later use as an energy source when needed. Around 50g of white fat cells stores more than 300 calories (technically kilocalories, for the scientists out there). Brown fat cells, on the other hand, actually break down fat to create heat. 50g of brown fat can burn up to 300 calories (kcal) in one day. Infants have a lot of brown fat (about 5% of their body mass) to keep them warm, and it was originally thought that brown fat disappeared from our bodies after infancy. Recently, however, scientists discovered that brown fat persists into adulthood and continues to help us stay warm in the cold. When we are exposed to cold temperatures, our bodies can increase the amount of brown fat cells to produce more heat, thereby burning more calories. Interestingly, shivering and endurance exercise both release a protein called irisin, which can help convert some white fat into brown fat. Some scientists think that brown fat might actually help protect against obesity. 

So the next time you look out the window and see this, think of it as a golden opportunity to increase your brown fat stores!

We have a fair number of clients who come into the gym and tell us their goal is to lose weight. What they actually mean is that they want to lose body fat and change their body composition. Usually this is for our clients’ own perceived aesthetics, though some clients might also be motivated by health factors. The truth is that people can be healthy across a large range of body fat percentages, sizes, and weights. The Health At Every Size movement promotes healthy eating and physical movement with the goal of improving one’s health, not necessarily losing weight. The movement sites numerous studies that show that weight and BMI (body mass index) are poor predictors of disease and longevity, and that being 5 pounds underweight is likely to be more harmful than being 75 pounds overweight. There is also growing evidence that increased physical activity alone, even without changes in body composition or weight, is enough to improve virtually all markers of cardiovascular health.

But what if your goal is still to lose fat for your own aesthetic or athletic performance reasons? Both exercise and nutrition are important components of that, but studies show that if you just diet, the weight that you lose will be a combination of both fat and muscle. Losing muscle means that you are slowing down your metabolism, which is the opposite of what you want to do when you are trying to lose body fat. Plus, muscle is what allows us to perform at our best in our daily lives. Two things have been shown to help preserve muscle while losing weight: doubling the recommended daily protein intake (1.6g of protein per kilogram of body weight instead of 0.8g) and regular strength training.

At The ShockYard, we focus mainly on strength training for a number of reasons, too many to go into in one blog post, but here, then, are two important ones:

1. If losing body fat is important to you, strength training ensures that you are maintaining and increasing your lean muscle mass at the same time, rather than losing muscle along with fat.
2. Our hope for all our clients is simply that they are healthy and happy. Increased physical activity through strength training improves cardiovascular health markers, decreases the risk of injury, and makes people feel stronger and more capable in their daily lives. 

So that’s the skinny on fat. Thanks for reading and have a happy, healthy day!