Tuesday, February 18, 2014

Of Liars & Grunters: More Than 500kcal/day That's the Minimal Amount of Energy >37% Overweight Subjects Don't Report. Plus: Grunt Your Way to a Powerful Serve

"Don't tell!" or "Shut up!" - What could the lady on the top possibly be meaning?
It's not always feasible to find exciting new studies everyday - specifically if you are already grunting under an unbearably high workload.... ok, you got me: That was a pun and a pretty bad one. "Grunting" is after all the topic of one out of two of the studies I am going to discuss in today's installment of On Short Notice. Moaning tennis players, to be precise. Nasty? I totally agree, but it obviously helps them to serve harder.

Apropos harder! Dieting is pretty hard and acknowledging that your failure may be the result of your inability to stick to your diet and not the 2g of carbs that are still left in your "healthy low carb diet", s not exactly something overweight and obese men and women like to do. With >37% of the overweight participants of a large scale epidemiology not reporting 500kcal or more of their daily energy intake, you will even have to ask yourself, how useful, let alone reliable the insights from corresponding studies actually are.
  • Fat under-reporting - study compares reported to real energy intake in  30 445 men and women who participated in the Cancer (EPIC-Norfolk) study. I suppose you won't be surprised that the number of "liars" or "forgetters", i.e. people who did not tell the researchers the truth about their actual dietary intake was significantly higher in overweight individuals.
    Figure 1: Underreporting of less than 250kcal per day may not matter. The fact that more than 37% of the overweight individuals sneak in way more than 500kcal per day is yet something you should always keep in mind, when you talk about / evaluate the results of weight loss interventions (Lentjes. 2010)
    If you take a closer look at the data in Figure 1 you will also realize that being female and normal-weight appears to cause a minimal forgetfulness with respect to the amount of food a person consumed during a 24h period as well - but let's be honest, I like this better than the crazy calorie-counter who weighs not just herself and her food, but also her poops.

    If we take into consideration, that more than 37% of the obese individuals will keep 500kcal and more from the researchers, this tells you something about the questions people voice about the significance of caloric deficits ... and it begs the question whether overweight individuals lie to the researchers, lie to themselves or simply don't realize that they are eating too much.
  • Grunting makes tennis players serve faster, but does not impact VO2 kinetics - I am 100% sure I mentioned this before: The moaning and groaning on the center court is not Venous Williams ripping her shirt off and jumping at the judge, it's a (often female) way to get the most out of every stroke.

    In their most recent paper, Emily R. Callison et al. were able to show that in their 10 members of the men’s (n=5) and women’s (n=5) tennis teams at a Division I university who had just completed their indoor competitive season the grunting did increase the ball velocity by 3.8%, but it did not have significant physiological effects on the athletes.

    Whether I can or want to agree with the researchers suggestion that "[i]t may be worthwhile for players and coaches in tennis, as well as other sports, to experiment with grunting to determine possible improvement in performance" is albeit something I am not so sure of :-/
SuppVersity Suggested Read: "Losing Weight Is Easy. Staving It Off Ain't: A Lesson in High vs. Very High Energy Restrictions - What's More Effective?" | read more
Bottom line: Grunt and be honest and your performance will increase - the one on the center court and the one on the scale in your bathroom ;-) All jokes aside, you can probably forget about the tennis study, but the extent to which people "lie" (as mentioned before, they may simply not be aware of how much they actually eat) about their energy intake is something you must not forget - irrespective of whether you're working as a personal coach or just an avid reader of scientific papers. If a study says that the weight loss was way below what you'd expect from an energetic perspective, this may oftentimes a necessary consequence of the fact that the energy deficit was just as far, if nor further away from where the researchers expected it to be.
  • Lentjes, Marleen AH, et al. "Dietary intake measurement using 7 d diet diaries in British men and women in the European Prospective Investigation into Cancer-Norfolk study: a focus on methodological issues." British Journal of Nutrition (2014): 1-11. 
  • Callison, Emily R, et al. "Grunting in Tennis Increases Ball Velocity But Not Oxygen Cost" Journal of Strength & Conditioning Research (2014): POST ACCEPTANCE, 9 February 2014
    doi: 10.1519/JSC.0000000000000333