Re: My husband has diabetes

x-no-archive: yes

Nicky wrote:

Any athlete who's carb-burning needs to carb up a little time before
extended energy expenditure - or they'll hit that "wall" that us
fat-burners don't have to worry about. My marathon-running BIL always
had a huge plate of pasta before a race...


They might be better off if they trained without carbing up, then used energy gel to get through the race instead, as needed. That way, they're able to burn longer lasting fat stores for energy, and less likely to bonk when low, and can stay in fat burning mode by only consuming as much dextrose as they need to fuel the race.

Lots of marathoners hit the wall despite carbing up; and once they exhuast their muscle glycogen, if they're not accustomed to fat burning, they're screwed. :-)


Here's an interesting study with endurance athletes:

Metabolism. 1983 Aug;32(8):769-76. Related Articles, Links

The human metabolic response to chronic ketosis without caloric
restriction: preservation of submaximal exercise capability with
reduced carbohydrate oxidation.

Phinney SD, Bistrian BR, Evans WJ, Gervino E, Blackburn GL.

To study the effect of chronic ketosis on exercise performance in
endurance-trained humans, five well-trained cyclists were fed a
eucaloric balanced diet (EBD) for one week providing 35-50 kcal/kg/d,
1.75 g protein/kg/d and the remainder of kilocalories as two-thirds
carbohydrate (CHO) and one-third fat. This was followed by four weeks
of a eucaloric ketogenic diet (EKD), isocaloric and isonitrogenous
with the EBD but providing less than 20 g CHO daily. Both diets were
appropriately supplemented to meet the recommended daily allowances
for vitamins and minerals. Pedal ergometer testing of maximal oxygen
uptake (VO2max) was unchanged between the control week (EBD-1) and
week 3 of the ketogenic diet (EKD-3). The mean ergometer endurance
time for continuous exercise to exhaustion (ENDUR) at 62%-64% of
VO2max was 147 minutes at EBD-1 and 151 minutes at EKD-4. The ENDUR
steady-state RQ dropped from 0.83 to 0.72 (P less than 0.01) from
EBD-1 to EKD-4. In agreement with this were a three-fold drop in
glucose oxidation (from 15.1 to 5.1 mg/kg/min, P less than 0.05) and a
four-fold reduction in muscle glycogen use (0.61 to 0.13 mmol/kg/min,
P less than 0.01). Neither clinical nor biochemical evidence of
hypoglycemia was observed during ENDUR at EKD-4. These results
indicate that aerobic endurance exercise by well-trained cyclists was
not compromised by four weeks of ketosis. This was accomplished by a
dramatic physiologic adaptation that conserved limited carbohydrate
stores (both glucose and muscle glycogen) and made fat the predominant
muscle substrate at this submaximal power level.

PMID: 6865776 [PubMed - indexed for MEDLINE]
.

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