Race-Pack Weight

With a month to go to the 2013 Kalahari Augrabies Extreme Marathon (KAEM) the time has come to have a look at race-pack weight. The Marathon des Sables research data, once again, provides some interesting insight.

At first there seems to be some correlation between performance and pack-weight. As can be seen, those in the top 10% of the field had a wet start weight of 8.5kg’s and those in the bottom 10% a wet pack-weight that exceeded 10kg’s.

Race-Pack Weight (kg) Start Weight (Wet) at Start of the Race (Average)
Position 1 to 100	Position 101 to 300	Position 301 to 700	Position 701 to 900	Position 901 to 1000
8.5	8.8	9.1	9.4	10+

If we exclude the water each participant had on the start line then the top 10% had an average start weight of around 7kg’s while the bottom 10% of the field had a pack weight of around 8,5kg’s. Runners in the middle of the field had a wet start weight of 9,1kg and a dry weight of 7,6kg’s.

This, however, provides only part of the answer. Looking at the ratio of pack-weight to the body weight of the runners, provide an average across the entire field of between 12 and 13%. Even among the top 10% of runners the pack-weight range is between 9% and 19% of the runner’s body weight. The bottom 10% of the field has a pack-weight to body weight range of 11% to 17%. The pack weight range that links pack-weight to race position, therefore, seems somewhat tenuous. What appears to be more relevant is the relationship between pack-weight and the runner’s body weight. The body-weight to pack-weight percentage range that fits across the entire performance of the field falls between 9% and 15%. 

In Practical Terms

So what does this mean in practical terms, a 70kg male runner running a 245km distance would require 15,607 kCal’s for the race (based upon MdS research). At a 70% Carbohydrate, 25% Protein and 5% Fat composition the runner’s food will weigh around 3,251kg’s (excluding packaging), if we factor-in package weight then food weight will come in at around 3,5kg’s. Add to this the water and water bottle weight, the pack weight, mandatory equipment etc. Additional luxury items such as warm clothing for night time, non-running shoes, comfort items (sleeping mat etc.), extra clean running clothes and underwear, photographic equipment and other electronics (such as MP3 player, GPS charger etc.) should also be added, although much of the latter would be subject to personal preference.

I am, therefore, somewhat sceptical when claims are made of race packs that weigh-in at 6,5kg’s, or below, on the start-line as this would imply a dry weight of 5kg’s. Working back from this, there is simply not enough weight left in the equation to account for all mandatory food and equipment. By extracting mandatory equipment from the 5kg’s would result in a food compliment of around 2,6kg’s (packaging included). I estimate that this would translate into around 2,37kg’s worth of food, or stated differently, this would translate at best to 13,534kCal’s which is 465kCal’s less than what the race regulations typically require.

Looking more specifically at an extremely “lean” Marathon des Sables performance race pack, I can get to 6,7kg’s, but even this seems somewhat unrealistic except for the most committed and hard-core runners. Below is a table that provides some insight into how lean the race-pack will have to be to reach 6,7kg’s.    

Content	Item Weight (grams)	Accumulated Pack Weight (grams)
Mandatory Items (for 2013 MdS)
1.       Race-Pack (no front pack)	550	550
2.       750ml Water Bottles x 2 (bottle with holder)	360	910
3.       Food (12,000kCal’s)*1, *2 [I am very optimistic here!]	2,571	3,481
4.       Water (1,5liter)	1,500	4,981
5.       Sleeping Bag	400	5,381
6.       Head Torch	60	5,441
7.       Anti-Venom Pump	76	5,517
8.       Compass	28	5,545
9.       Lighter	15	5,560
10.   Whistle	15	5,575
11.   Knife	232	5,807
12.   Signalling Mirror	30	5,837
13.   Survival Sheet	60	5,897
14.   Disinfectant	100	5,997
15.   Pot/Bowl plus Spoon/Fork	170	6,167
Non-Mandatory Items but Vital for the Race (for 2013 MdS)
16.   Hygiene Items (Soap, Cloth, Toothbrush, Toilet-roll etc.)	407	6,574
17.   Weight Adjustment	120	6,694
Note: *1During the 2013 MdS only provision for six and not seven days had to be carried. The usual final (7th day) was no longer part of the official race but formed part of a fun-run. *2 With the MdS 2013 spread over 223km’s and the average runner weighing in at 70kgs the “optimal” energy requirement for the MdS is closer to 0.91kCal/kg/km or 14,205kCal. This means that the difference between the minimum calories and the actual calories requires a weight adjustment of 120g.

Conclusion

This brings me to an important point which speaks to the spirit of the sport. Ultra-endurance events and in particular self-sufficiency multi-stage events are events which is aimed at the individual. It places the individual against his or her own abilities, tests individual mental and physical strength combined with strategy and endurance. To succeed therefore in something like the MdS, KAEM or any other multi-stage adventure race has less to do with your overall ranking and much more to do with how you manage yourself before and during the event, this absolutely, relates to how you prepare, what you take with, and how well you take care of yourself and all of this within the realm of self-sufficiency. If you have the genetic ability, backed by training and race strategy to place in the top position then that is great, however, if you are not genetically programmed to compete at that level then placement is less relevant. What is important, however, is that placement should not undermine the spirit of the event.

I was somewhat perturbed when a few of the top-ten percent runners (and I stress only a few) went from tent to tent to scrounge additional food etc. This would imply that they had not taken sufficient food, which speaks to a faulty strategy at best or to an intentional deficiency driven by the unhealthy desire to reduce pack weight. The former would, in my opinion fall well within the spirit of the sport with assistance from other runners showing the support that an event like this fosters. The latter, however, would fall well beyond the spirit of the event.

What I have learned from analysing the MdS research data is that a reasonable weight would be somewhere between 12 and 13-percent of a runner’s body-weight  With this as a guide it should be much simpler to plan race-pack content.

Within the next week or two I will publish my KAEM race pack content with specific weights, the aim would be to see if I can lower my MdS race weight even further.

Thank you for reading my blog.

Genis