\n\u201cMy quick answer has always been 10% of your body weight.\u00a0 If you weight 80kg, that\u2019s 8kg, and you in have to account for the weight of the sled. If you are low on cash, simply use a car or truck rubber tire, and use sandbags for additional weight. Why 10%? Because Charlie Francis said so.
\nBut serious, he did say 10%, and we experimented with it.\u00a0 We found going too high, say 20%, the athletes were struggling to keep the same form and the ground contact was substantially increased.\u00a0 I don\u2019t have any scientific proof of that, but you can just see and hear it.
\nIn this month\u2019s Journal of Strength & Conditioning Research, May 2014, Vol28, No.5, pg. 1241-1245, they studied the effects of Sled Towing on Sprint Starts.
\nThe results are suggesting 20% weight on sleds instead of 10%.\u201d\u00a0 End of citation.
\nMy idea: the weight of the sled is not all that important, if one is sprinting on a wet synthetic track e.g. after rain, the weight could be very high, but the lack of friction still would result in low added resistance. So the weight, expressed in kgs of lbs or in percentage of body weight is of no value.
\nMy concept is that the added weight and friction (= resistance) should result in a time loss of more than 10% of the time compared to the time ran without the resistance.
\nSo if your 30 meter standing start is 4.00, than with resistance (any kind of resistance), one should not be running the 30 meter standing start slower than 4.40.
\nIt strikes me as strange that the article in JSCR also uses the body weights percentage as a parameter to judge the resistance. Apart from the fact that they did not really measure the training effects of the 10% vs 20% sled over time.
\nPS. Charlie anyhow wasn\u2019t a fan of resisted sprinting nor of assisted or supramaximal sprinting, but if he really spoke about 10% of body weight it just shows that not all of his ideas were right.<\/p>\n
![\"My](\"https:\/\/helpingthebesttogetbetter.com\/wp-content\/uploads\/2014\/05\/Resisted-sprinting-sled.jpg\")
<\/a>Here is another one: there are more ways to interpret research:
\nCrossfit-Based High-Intensity Power Training Improves Maximal Aerobic Fitness and Body Composition by Smith, Michael M.; Sommer, Allan J.; Starkoff, Brooke E.; JSCR 27(11):3159-3172, November 2013.
\nThe main outcome of the study is that a 10 week HIPT (crossfit) increased VO2max in men from 43.10\u00b11.40 to 48.96\u00b11.42 ml\/kg\/min and in women from 35.98\u00b11.60 to 40.22\u00b11.62 ml\/kg\/min.
\nAlso the researched measured a decreases in fat percentage of 22.2\u00b11.3 to 18.0\u00b11.3 in males and in females from 26.6\u00b12.0 to 23.2\u00b12.0.
\nWell, isn\u2019t that great new for the crossfit fans?\u00a0 Yes, it looks like it: losing fat and improving VO2max without \u201creal\u201d boring cardio stuff like on treadmills or bikes.<\/p>\n
But……. the critical reader also would have read that:<\/p>\n
Citation 1: \u201cSubjects had already been following a \u201cPaleolithic\u201d type diet prior to and following completion of the training protocol\u201d
\nSo was the loss in fat due to the crossfit program or to the diet?<\/p>\n
Citation 2: \u201c16% of total recruited subjects) citing overuse or injury for failing to complete the program and finish follow up testing\u201d Are you still with me? The program managed to injure 16% of the participants in only10 weeks?
\nCan you afford to lose 16 % of your athletes in only10 weeks? Well…….. I can\u2019t!
\nHow many athletes would be left after a years on this program?<\/p>\n
Let these articles be an example of how careful and critical one has to be in reading, interpreting and applying information.\u00a0 The effort of your athletes and your time are probably too valuable to waste.<\/p>\n","protected":false},"excerpt":{"rendered":"
And our world is full of them, here is a misunderstanding about a popular issue in sprints training and a questions that I have heard since I started working with this: \u201cAs far as resisted …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-723","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/helpingthebesttogetbetter.com\/index.php?rest_route=\/wp\/v2\/posts\/723","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/helpingthebesttogetbetter.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/helpingthebesttogetbetter.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/helpingthebesttogetbetter.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/helpingthebesttogetbetter.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=723"}],"version-history":[{"count":3,"href":"https:\/\/helpingthebesttogetbetter.com\/index.php?rest_route=\/wp\/v2\/posts\/723\/revisions"}],"predecessor-version":[{"id":727,"href":"https:\/\/helpingthebesttogetbetter.com\/index.php?rest_route=\/wp\/v2\/posts\/723\/revisions\/727"}],"wp:attachment":[{"href":"https:\/\/helpingthebesttogetbetter.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=723"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/helpingthebesttogetbetter.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=723"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/helpingthebesttogetbetter.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=723"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}