Looking Closer at the Athlete’s Blood Sugar Study

In Heart Rate Training – Part 9, I took a look at a really interesting 2016 study on Blood Sugar levels in athletes (Felicity Thomas, BE(Hons), Chris G. Pretty, PhD, Thomas Desaive, PhD, and J. Geoffrey Chase, PhD. Blood Glucose Levels of Subelite Athletes During 6 Days of Free Living. J Diabetes Sci Technol. 2016 Oct; 10(6): 1335–1343).

The study looked at ten athletes and their blood sugars. They discovered that four of the ten athletes were pre-diabetic. Let’s take a look and see what additional information we can tease from the data.

The study had three females and seven males.

All but 4 participants consumed on average an amount of carbohydrate that was between 45 and 65% of their recommended daily calorie intake.

Ath05, Ath07 and Ath09 have elevated fasting glucose within the prediabetes range 5.6-6.9 mmol/L suggested by the ADA.

The mean PPGR ranges from 0.2 to 2.0 mmol/L.hr displaying a wide range intra and inter of carbohydrate sensitivity.

Fortunately, they included some of the data on the participants.

Subject Sex Age BMI PBF (%) FFM (kg) FBG (mmol/L) FPI (mU/L) FIS (mU/L.min) TIB-MR (%) Mean PPGR (mmol/L.hr) Mean PPG (mmol/L) Exercise (min/day) VO2max (mL/kg/min)
Ath01 F 23 21.6 25.3 45 5.2 9 1319 86.6 1.1 6.1 84 39
Ath02 M 23 21.9 5.1 6.3 913 90.7 0.5 6 41 60
Ath03 M 50 26.4 4.7 11.8 1878 76.1 1.9 6 68 39
Ath04 M 23 20.4 5.1 64.8 4.6 6.5 832 99.2 0.5 5.5 93 67
Ath05 M 28 24.2 14.1 60.6 6 6.3 820 30.7 0.9 6.8 158 59
Ath06 M 36 22.4 15.5 63.3 4.4 8.3 1844 94.3 1.2 5.9 28 59
Ath07 M 37 26 19.7 65.3 6.7 10.5 1553 23.9 1.1 7.1 20 42
Ath08 M 22 24.5 13.2 70.6 5.5 11 1550 31.7 0.2 5.5 24 37
Ath09 F 37 21.1 17.8 46.7 6 6 936 9.7 2 7.4 102 47
Ath10 F 27 22.2 28.3 47.7 5.2 9.5 1344 86.6 1 6.7 42 44
  • FBG, fasting blood glucose;
  • FFM, fat free mass;
  • FIS, fasting insulin secretion;
  • FPI, fasting plasma insulin;
  • Maxppg, maximum blood glucose value reached after a meal; PBF, percentage body fat;
  • PPG, blood glucose value 2 hours after a meal;
  • PPGR, postprandial glucose response;
  • TIB-MR, time in band, with meals removed.
  • Body composition analysis results were not available for Ath02 and Ath03, hence PBF and FFM values are missing.

Ath03 – Unique Case

Let’s focus in on Ath03. This athlete is a 50-yr old male who has a good fasting glucose number at the same time as a high fasting Plasma Insulin and high fasting Insulin Secretion number. As the paper states:

A subject can achieve good overall control or even experience low BG, such as Ath03, but still demonstrate a high mean PPGR indicating a high sensitivity to carbohydrates.

Here is a really interesting note:

Ath03 consumed on average ~150 g of carbohydrate less than the lower recommended limit, 1770 kcal less than required (Table 2) and was the only participant to demonstrate a significant amount time below 4.0 mmol/L.

The study stated:

Athletes are traditionally encouraged to consume high carbohydrate diets to replenish muscle glycogen stores and improve performance, with a particular focus on postexercise carbohydrate consumption. However, this advice may be negatively impacting the blood sugar levels of athletes predisposed to have a low tolerance of carbohydrates.

This is exactly my concern. Are weekend warriors fueling themselves as if they are elite athletes and suffering metabolic damage as a result?

 

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