Greetings fellow hiker!
I have been a pretty avid hiker for 20+ years. Recently, I heard a fellow hiker state that "rest breaks when hiking should be less than 5 minutes or more than 20 minutes to avoid a lactic acid build up". While I love this rule for time managment when hiking with a group, I cannot find evidence to support the justification of less than 5 minutes or more than 20. If anyone could provide supporting evidence or give other evidence for this rule of thumb, it would be greatly appreciated. I often lead groups in hiking and I certainly don't want to be using false information to manage the outing, the proper education can really enrich the experince.
Always an interesting topic in our Scout troop for both the Scouts and adults. Relatively simple day hikes can incur longer durations between less-frequent stops. Our troop usually follows a guideline of 1-2 short rests per hour, with a longer break say at 0900, 1200 (lunch) and 1500 if we're out for 9-12 hours. Backpacking is another matter. We follow the guideline of more-frequent "packs-on" breaks of a few 2-3 min breaks per hour, with one 20-30 min "packs-off" break every 90-120 mins depending on terrain. The shorter breaks allow you to catch your breath and slow your heartrate a little, but still keeps your muscles and joints warm and loose. Also just enough time for everyone to take a hit from their Nalgene. The less-frequent but longer breaks without packs allows your body to recover and gives you time for refuel snacking. This guideline isn't so much for lactic acid avoidance as it is to keep exuberant teenage Scouts focused and able to keep moving without the whole caravan grinding to a halt every time we stop for a break.
Even after a day of steep ascents/descents with a full pack I've never personally felt soreness during the day. It's only after I've relaxed in camp for several hours or later in the tent that the soreness sets in. But at 52 y.o. I also usually take a prophylactic dose of Aleve before I turn-in for the evening. Works wonders...