[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"public-library:en-GB:workout:running-short-intervals-15-15":3},{"slug":4,"sport":5,"category":6,"level":7,"intensity_unit":8,"modified_at":9,"author":10,"head":11,"equipment":14,"sources":17,"content":25,"facts":210,"blocks":446,"related":521},"running-short-intervals-15-15","running","vo2max","intermediate","pace","2026-10-25","Pierre Halloo",{"title":12,"description":13},"15\u002F15 running intervals: 3 × 12 at vVO2max","15\u002F15 running intervals in 3 sets of 12: 15 s at vVO2max, 15 s of steady running at 70%. Distances for 14 to 18 km\u002Fh, and the recovery trap. 47 min.",[15,16],"gps_watch","track",[18,21,23],{"citation":19,"url":20},"Billat V. L. et al., Int J Sports Med 2001;22(3):201-208",null,{"citation":22,"url":20},"Helgerud J. et al., Med Sci Sports Exerc 2007;39(4):665-671",{"citation":24,"url":20},"Rozenek R. et al., J Strength Cond Res 2007;21(1):188-192",{"h1":26,"summary":27,"purpose":38,"execution":82,"feel":104,"mistakes":111,"not_for":148,"faq":155,"evidence":201},"15\u002F15 running intervals (3 × 12)",{"type":28,"children":29},"root",[30],{"type":31,"tag":32,"props":33,"children":34},"element","p",{},[35],{"type":36,"value":37},"text","15\u002F15 running intervals: three sets of 12 × 15 seconds at 100% of your vVO₂max, with 15 seconds of steady running at 70% between reps. 9 minutes at that speed in a 47-minute session. The efforts are short; the hard part is never easing off on the recoveries.",{"adaptation":39,"for_whom":51,"when":67},{"type":28,"children":40},[41,46],{"type":31,"tag":32,"props":42,"children":43},{},[44],{"type":36,"value":45},"The 15\u002F15 trains your vVO₂max, your aerobic power, with efforts so short they cost your legs very little. The trick isn't in the 15 fast seconds but in the 15 that follow: at 70% of vVO₂max you're still running, and your breathing doesn't have time to settle. From one rep to the next, your oxygen uptake stays high.",{"type":31,"tag":32,"props":47,"children":48},{},[49],{"type":36,"value":50},"That's what Billat's 2001 study showed: at the same average intensity, a 15\u002F15 at 100% with recoveries at 70% gave roughly twice as much time at VO₂max as one run faster on the effort and slower on the recovery. Running faster on the effort and then recovering more slowly throws away most of what makes the format work.",{"type":28,"children":52},[53],{"type":31,"tag":32,"props":54,"children":55},{},[56,58,65],{"type":36,"value":57},"Runners who've already done a few short-interval sessions, a ",{"type":31,"tag":59,"props":60,"children":62},"a",{"href":61},"\u002Fen-GB\u002Flibrary\u002Frunning\u002Fvo2max\u002Frunning-short-intervals-30-30",[63],{"type":36,"value":64},"30\u002F30",{"type":36,"value":66}," for instance, and who prefer short reps to long efforts. It also works when you're coming back to training, with fewer sets, and it's widely used in team sports. You need a recently measured vVO₂max: over 15 seconds, being out by a km\u002Fh or two changes the whole session.",{"type":28,"children":68},[69],{"type":31,"tag":32,"props":70,"children":71},{},[72,74,80],{"type":36,"value":73},"One vVO₂max session a week is usually enough: the 15\u002F15 can alternate with a 30\u002F30 or a ",{"type":31,"tag":59,"props":75,"children":77},{"href":76},"\u002Fen-GB\u002Flibrary\u002Frunning\u002Fvo2max\u002Frunning-intervals-1min-1min",[78],{"type":36,"value":79},"1-minute session",{"type":36,"value":81}," from week to week. Put it after an easy day or a rest day, never the day before a long run, another hard session or a race. To progress, add a fourth set while keeping the 100%\u002F70% pairing, then move on to longer efforts.",[83,90,97],{"type":28,"children":84},[85],{"type":31,"tag":32,"props":86,"children":87},{},[88],{"type":36,"value":89},"10 minutes of easy running at 60–65% of vVO₂max, then 5 minutes at 66–72%. Meanwhile, set out your cones: at 16 km\u002Fh, one at 67 metres for the effort, then another 47 metres further on for the recovery.",{"type":28,"children":91},[92],{"type":31,"tag":32,"props":93,"children":94},{},[95],{"type":36,"value":96},"Three sets of 12 × 15 seconds at 100% of your vVO₂max, each followed by 15 seconds at 70%, with 2 min 30 of walking between sets. At 16 km\u002Fh that's 67 metres in 15 seconds at 3:45\u002Fkm, then 47 metres of recovery at 5:21\u002Fkm. The recovery isn't a gentle jog: it's steady running, and it's what makes the session. Don't go faster than your vVO₂max on the efforts, even if it feels slow at first.",{"type":28,"children":98},[99],{"type":31,"tag":32,"props":100,"children":101},{},[102],{"type":36,"value":103},"10 minutes of very easy running at 55–65% of vVO₂max. If you couldn't hold the 70% recovery to the end of the last set, make a note: next time, drop a set rather than slowing the recovery.",{"type":28,"children":105},[106],{"type":31,"tag":32,"props":107,"children":108},{},[109],{"type":36,"value":110},"The 15-second efforts feel almost easy. The recoveries, though, never let you catch your breath, and by the second set the fatigue settles into your legs. Thirty-six reps: counting them becomes an event in itself. Guide: 7 out of 10.",[112,121,130,139],{"title":113,"body":114},"Slowing the recovery",{"type":28,"children":115},[116],{"type":31,"tag":32,"props":117,"children":118},{},[119],{"type":36,"value":120},"The mistake that empties the session of its point. Jog at 50% instead of running at 70% and your breathing settles between efforts. Rozenek and colleagues measured a clearly lower share of VO₂max in a 15\u002F15 with slow recoveries.",{"title":122,"body":123},"Running faster than your vVO₂max",{"type":28,"children":124},[125],{"type":31,"tag":32,"props":126,"children":127},{},[128],{"type":36,"value":129},"Over 15 seconds it's easy to end up sprinting. In Billat's study, running faster than vVO₂max on the efforts halved the time spent at VO₂max. The right speed is your vVO₂max, no more, from the first rep to the last.",{"title":131,"body":132},"Running without markers",{"type":28,"children":133},[134],{"type":31,"tag":32,"props":135,"children":136},{},[137],{"type":36,"value":138},"Over such a short time, your watch can't give a reliable pace. Put out cones at your distances, or use the markings on a track: it's the only way to hold the right speed.",{"title":140,"body":141},"Mixing it up with the supramaximal 15\u002F15",{"type":28,"children":142},[143],{"type":31,"tag":32,"props":144,"children":145},{},[146],{"type":36,"value":147},"Another 15\u002F15 is run at 115–120% of vVO₂max with walked recoveries: that's a speed session, not a vVO₂max one. Same notation, different effect.",{"prerequisites":149,"avoid_if":152},[150,151],"A recently measured vVO₂max: every distance depends on it.","A few short-interval sessions already done, such as a 30\u002F30.",[153,154],"You have pain or a recent injury, especially in your calves or hamstrings: the repeated accelerations load them.","A long run, another hard session or a race is planned for the next day.",[156,165,174,183,192],{"question":157,"answer":158},"How fast should you run 15\u002F15 intervals?",{"type":28,"children":159},[160],{"type":31,"tag":32,"props":161,"children":162},{},[163],{"type":36,"value":164},"At 100% of your vVO₂max on the effort and 70% on the recovery. At 14 km\u002Fh that's 58 metres in 15 seconds, then 41 metres of recovery; at 16 km\u002Fh, 67 then 47 metres; at 18 km\u002Fh, 75 then 53 metres. Put cones at those distances: over 15 seconds, they're more reliable than your watch.",{"question":166,"answer":167},"Active or passive recovery in a 15\u002F15?",{"type":28,"children":168},[169],{"type":31,"tag":32,"props":170,"children":171},{},[172],{"type":36,"value":173},"Active, and brisk: 70% of vVO₂max, proper running, not a shuffle or a walk. That recovery keeps your breathing high and is what makes a 15\u002F15 worthwhile. Only the 2 min 30 breaks between sets are walked.",{"question":175,"answer":176},"15\u002F15 or 30\u002F30: which should I choose?",{"type":28,"children":177},[178],{"type":31,"tag":32,"props":179,"children":180},{},[181],{"type":36,"value":182},"The 30\u002F30 is simpler to start with: 30 seconds gives you time to feel the pace, and the recovery is a jog. The 15\u002F15 is choppier and needs a faster recovery, at 70%. Both target vVO₂max; you can alternate them from one week to the next.",{"question":184,"answer":185},"Is a 15\u002F15 as effective as 4 × 4 minutes?",{"type":28,"children":186},[187],{"type":31,"tag":32,"props":188,"children":189},{},[190],{"type":36,"value":191},"In Helgerud's 2007 study, over 8 weeks and with equal work, a 15\u002F15 raised VO₂max a little less than 4 × 4 minutes. Both worked. The 15\u002F15 remains a good option if long efforts don't suit you, or simply for variety.",{"question":193,"answer":194},"How many sets of 15\u002F15 should a beginner do?",{"type":28,"children":195},[196],{"type":31,"tag":32,"props":197,"children":198},{},[199],{"type":36,"value":200},"Two sets of 12 if the format is new to you, then three once the 70% recovery holds to the end. Always keep the 100%\u002F70% pairing: better to do fewer sets than to slow the recovery.",{"level":202,"text":203},"moderate",{"type":28,"children":204},[205],{"type":31,"tag":32,"props":206,"children":207},{},[208],{"type":36,"value":209},"Billat and colleagues (Int J Sports Med 2001) compared three 15\u002F15s with the same average intensity, about 85% of vVO₂max: 90\u002F80, 100\u002F70 and 110\u002F60%, in 7 runners aged around 52 (mean vVO₂max 15.9 km\u002Fh). The 90\u002F80 and 100\u002F70 formats gave about 14 minutes at VO₂max, against 7 for the 110\u002F60; the authors conclude you shouldn't go above 100% of vVO₂max. Helgerud and colleagues (Med Sci Sports Exerc 2007), in 40 moderately trained men over 8 weeks at 3 sessions a week with equal work: VO₂max +5.5% with a 15\u002F15 (47 reps, heart-rate targets) against +7.2% with 4 × 4 minutes. Conversely, Rozenek and colleagues (J Strength Cond Res 2007) measured a low fraction of VO₂max (71.6%) in a 15\u002F15 at 100% with recovery at 50%. The 100%\u002F70% pairing comes from Billat; the 3 × 12 split, the walking breaks, the warm-up and the cool-down are Wattson choices. Bottom line: good evidence on the immediate response, moderate on training 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