Eat fat for endurance

Here is an intriguing one:

Significant effect of a pre-exercise high-fat meal after a 3-day high-carbohydrate diet on endurance performance

These results suggest that ingestion of a HFM (high fat meal) prior to exercise is more favorable for endurance performance than HCM (high carb meal). 

So maybe bacon and eggs would be better than that pasta party before the marathon.....

The Runner's High - you are destined to enjoy exercise

I saw this report pass over my Google Reader today, based on a study just published in the Journal of Experimental Biology:

Wired to run: exercise-induced endocannabinoid signaling in humans and cursorial mammals with implications for the ‘runner’s high’

Humans report a wide range of neurobiological rewards following moderate and intense aerobic activity, popularly referred to as the ‘runner’s high’, which may function to encourage habitual aerobic exercise. Endocannabinoids (eCBs) are endogenous neurotransmitters that appear to play a major role in generating these rewards by activating cannabinoid receptors in brain reward regions during and after exercise. Other species also regularly engage in endurance exercise (cursorial mammals), and as humans share many morphological traits with these taxa, it is possible that exercise-induced eCB signaling motivates habitual high-intensity locomotor behaviors in cursorial mammals. If true, then neurobiological rewards may explain variation in habitual locomotor activity and performance across mammals. We measured circulating eCBs in humans, dogs (a cursorial mammal) and ferrets (a non-cursorial mammal) before and after treadmill exercise to test the hypothesis that neurobiological rewards are linked to high-intensity exercise in cursorial mammals. We show that humans and dogs share significantly increased exercise-induced eCB signaling following high-intensity endurance running. eCB signaling does not significantly increase following low-intensity walking in these taxa, and eCB signaling does not significantly increase in the non-cursorial ferrets following exercise at any intensity. This study provides the first evidence that inter-specific variation in neurotransmitter signaling may explain differences in locomotor behavior among mammals. Thus, a neurobiological reward for endurance exercise may explain why humans and other cursorial mammals habitually engage in aerobic exercise despite the higher associated energy costs and injury risks, and why non-cursorial mammals avoid such locomotor behaviors.

They basically found that that exercising mammals release pleasurable endocanabinoids in response to exercise.

Having suggested that natural selection used the endocanabinoid system to motivate endurance exercise in humans and other animals that walk and run over long distances, Raichlen adds 'These results suggest that natural selection may have been motivating higher rather than low-intensity activities in groups of mammals that evolved to engage in these types of aerobic activities'.

There is some more background at Eureka here.

The team publish their discovery that animals that evolved for endurance exercise benefit from endocanabinoids while animals that did not don't experience the pleasures, leading them to propose that natural selection used the endocanabinoid system to motivate endurance exercise in humans.

Given that we do experience the runners' high, the implication is that we evolved for endurance....or were designed for endurance. 

It is also interesting from the perspective of motivation and the ideas of Samuele Marcora that I mentioned here.

Marathons are dangerous?

Maybe.  But maybe particularly if you are not used to running.

Post-Exercise Cardiac Troponin Release is Related to Exercise Training History

Average miles run per week in the last 3 years, a marker of total training experience, encompassing training volume and duration, was negatively associated with post-marathon cTnI release (p<0.001).

what happens if you walk 1000 miles in 1000 hours?

Last year I wrote my reading about Captain Barclay; his most famous exploit was the walking of 1,000 miles (1,600 km) in 1000 hours for 1000 guineas in 1809.  There is good analysis here.

Anyway, I just noticed that a case study has been published looking at the physiological impact of repeating this feat: (presumably it was Richard Dunwoody)  It sounds easy..one mile in 1 hour.....but doing that every hour for 1000 hours....little sleep, curtailed rest.  Hard stuff.



The biochemical, physiological and psychological consequences of a “1,000 miles in 1,000 hours” walking challenge

Abstract

The combined effects of 42 days of chronic sleep disruption and repeated hourly bouts of physical exertion have not been described. This case study reports the physiological and psychological demands placed on one individual who walked 1 mile in each consecutive hour for a period of 1,000 h (42 days), covering a total distance of 1,000 miles. The participant walked at a mean speed of 1.75 m/s completing each mile in approximately 15 min. Over the course of the challenge, the individual lost 1.6 kg in body weight. Markers of skeletal muscle damage, increased gradually whilst free testosterone levels decreased over the course of the challenge. Stress hormones increased whilst inflammatory markers (CRP) initially rose but then returned towards baseline over the course of the study. Cognitive motor performance measured via reaction time was maintained throughout the 42 days. The participant also displayed mood states typical of an elite athlete at baseline and throughout the challenge. Participation in this novel ‘1,000 mile 1,000 h’ walking challenge evoked considerable physiological stress in a fit, healthy middle-aged participant but did not markedly alter cognitive performance or mood over the 42-day period.

Chronic Cardio is healthy?

In our little paleosphere endurance exercise is usually characterised as a "bad" thing.  Mark Sission's Chronic Cardio post is the usual basis for all this, but there are other references too.  In general I agree with this view.  However sometimes other bits and pieces pop up that indicate a different viewpoint.  I saw this one the other day:

Autophagy-related and autophagy-regulatory genes are induced in human muscle after ultraendurance exercise

The purpose of this study was to evaluate whether ultra endurance exercise changes the mRNA levels of the autophagy-related and autophagy-regulatory genes. Eight men (44 ± 1 years, range: 38–50 years) took part in a 200-km running race. The average running time was 28 h 03 min ± 2 h 01 min (range: 22 h 15 min–35 h 04 min). A muscle sample was taken from the vastus lateralis 2 weeks prior to the race and 3 h after arrival. Gene expression was assessed by RT-qPCR. Transcript levels of autophagy-related genes were increased by 49% for ATG4b (P = 0.025), 57% for ATG12 (P = 0.013), 286% for Gabarapl1 (P = 0.008) and 103% for LC3b (P = 0.011). The lysosomal enzyme cathepsin L mRNA was upregulated by 123% (P = 0.003). Similarly, transcript levels of the autophagy-regulatory genes BNIP3 and BNIP3l were both increased by 113% (P = 0.031 and P = 0.007, respectively). Since upregulation of these genes has been related with an increased autophagic flux in various models, our results strongly suggest that autophagy is activated in response to ultra endurance exercise.

Autophagy is usually presented as a "good thing" - the self eating process by which cells clean themselves up, getting rid of waste products and some pathogens.  Often it is promoted by fasting and again in the paleo world it is one of the benefits that are claimed for intermittent fasting.  I've probably written about that in the past somewhere.

Anyway, this study seems to link it to ultraendurance exercise.....actually it is talking epigenetics as far as I can see, particular autophagy related genes being switched on.  I suppose this might make sense if the exercise has actually cause massive damage and the body is frantically trying to clear up and repair the mess.  Maybe not so positive.