Changes

It’s It's harder to run in hotter weatherthe heat, something that is easy to forget when toeing the line at a marathon. If you’ve you've set goals based on cool weather training or performance without taking the heat into account, you will go out too fast and your overall time will suffer. But how much does your performance change with temperature? I found You can't run as fast in the heat as the cool, but if you have a better idea what pace to set, you may be able to avoid a catastrophic result. There is good scientific evidence that [[Running in the Heat]] will slow you down, and there is a study<ref name="study"/> that gives some answersquantifies the slowdown. ==The Answer, Part 1==The study showed how finish time changes with temperature. The , and the results are shown in the following graph.

http[[File://jfsavage.smugmug.com/photos/817939120_uZxSb817939120 uZxSb-X3O.jpg]]

To explain how This graph works well for runners finishing the race at 3 hour pace or faster, but that excludes the majority of marathon runners. How can we extend this worksto slower runners? ==The Answer(s), Part 2==The approach I've taken is to assume the decline is linear from the end points of each curve, let’s use as shown by the colored lines. This will give us a couple projection of examplesperformance decline and I’ve created a table at the end of this page based on this assumption. You’ll need  [[File:818611486 iAHcm-O.jpg]] ==Perception of temperature==As noted in [[Running in the Heat]], exercising in mild conditions of 60f/15c significantly impacts performance, but the perception is one of fatigue rather than overheating. When pacing marathons, I have consistently found that runners in mild conditions between 50f/10c and 70f/20c seem to know be generally unaware of the heat index//feels like stress and instead feel fatigued. It can be hard to convince these runners to shed excess clothing, but once they cool off, they can often partly recover. Running marathon+ distance training runs on a frequent basis, I have found a similar phenomenon if I don't shed clothing fast enough to compensate for rising temperatures. My perception is of being a comfortable temperature , but feeling fatigued, often to the point of being sleepy. Shedding clothing so that I feel slightly cool greatly reduces the sense of fatigue, and my pace picks up even though my perceived effort remains the same. ==Your Mileage May Vary==There are a lot of flaws in this approach, which you expect at the raceshould be aware of. * This study uses only sub-3 hour marathon runners, and your projected cool weather their performancecharacteristics could be quite different to slower runners. * Runner A There is expecting to run a 2:40 marathon wide individual variation in cool conditionsperformance decline due to temperature. The level of heat adaptation the runner had, but the race is projecting 60 degreesbody size and shape, etc all play into this. * The 15C/59C line at lines in the 160 minute mark indicates graphs above are clearly not linear, so making this type of assumption is overly simplistic and probably excessively conservative. * Extrapolating information is a 3% drop in performanceflawed approach, so as there is no way of knowing what the corrected time actual data would be nearly 5 minutes slowerlook like. * Runner B ==Usability of the data==Given all these problems, is this approach usable or useful? I believe there is expecting to value as long as you understand the limitations of the approach. If the charts below say you can run a 34:30 48 marathon in based on your cool conditionsweather performance and the projected temperature, but the race this does not mean you can run a 4:48 in practice. What it does provide is projecting 70 degrees. The graph only goes a sense of just how much you will need to 3 hoursslow down on a hot day, so we and how important weather is in your results. Hopefully this information will assume allow you to reset your goals and promote a liner progression, which flexible approach on race day. ==Marathon Selection==One key note from this analysis is likely that weather will play a huge role in your results. If you are seeking a race to be too conservativeachieve a specific time goal, such as Boston Qualification, but will give us an ideachoosing a race that has a high probability of cool or cold weather becomes important. You are probably better off with a hillier course than warm weather for instance. At 3 hours, ==Projected Performance==Use the 'heat index' or 'feels like' temperatures rather than raw thermometer readings in the 20C/68C line table below. (The [[Perceived Temperature For Runners]] is quite different and should not be used here!) You can also get temperature adjustment via the [[VDOT Calculator]]. {| class="wikitable" | align="center" style="background:#f0f0f0;"|'''40f'''| align="center" style="background:#f0f0f0;"|'''50f'''| align="center" style="background:#f0f0f0;"|'''60f'''| align="center" style="background:#f0f0f0;"|'''70f'''| align="center" style="background:#f0f0f0;"|'''80f'''|-| 3:00:00||3:05:24 (3%)||3:10:48 (6%)||3:16:12 (9 percent. If we scale by %)||3:21:36 (12%)|-| 3:05:00||3:10:42 (3%)||3:16:25 (6%)||3:22:07 (10%)||3:27:49 (13%)|-| 3:10:00||3:16:01 (3%)||3:22:02 (7%)||3:28:03 (10%)||3:34:04 (14%)|-| 3:15:00||3:21:20 (4%)||3:27:40 (7%)||3:34:01 (11%)||3:40:21 (15%)|-| 3:20:00||3:26:40 (4%)||3:33:20 (8%)||3:40:00 (12%)||3:46:40 (15%)|-| 3:25:00||3:32:00 (4/%)||3:39:00 (8%)||3, that gives :46:01 (12%. On )||3:53:01 (16%)|-| 3:30 :00||3:37:21 (4%)||3:44:42 (9%)||3:52:03 (13%)||3:59:24 (17%)|-| 3:35:00||3:42:42 (5%)||3:50:25 (9%)||3:58:07 (210 minutes14%), ||4:05:49 (18%)|-| 3:40:00||3:48:04 (5%)||3:56:08 (9%)||4:04:12 (14%)||4:12:16 (19%)|-| 3:45:00||3:53:26 (5%)||4:01:52 (10%)||4:10:19 (15%)||4:18:45 (20%)|-| 3:50:00||3:58:49 (5%)||4:07:38 (10%)||4:16:27 (15% gives a corrected time of )||4:25:16 (21%)|-| 3:55:00||4:04:12 (5%)||4:13:24 (11%)||4:22:37 (16%)||4:31:49 (21%)|-| 4:00:00||4:09:36 (6%)||4:19:12 (11%)||4:28:48 (17%)||4:38:24 (22%)|-| 4:05:00||4:15:00 (6%)||4:25:00 (12%)||4:35:01 (17%)||4:45:01 (23%)|-| 4:10:00||4:20:25 (6%)||4:30:50 (12%)||4:41:15 (18%)||4:51:40 (24%)|-| 4:15:00||4:25:50 (6%)||4:36:40 (12%)||4:47:31 (19%)||4:58:21 (25%)|-| 4:20:00||4:31:16 (6%)||4:42:32 (13%)||4:53:48 (19%)||5:05:04 (26%)|-| 4:25:00||4:36:42 (7%)||4:48:24 (13%)||5:00:07 (20%)||5:11:49 (27%)|-| 4:30:00||4:42:09 (7%)||4:54:18 (14%)||5:06:27 (21%)||5:18:36 (27%)|-| 4:35:00||4:47:36 (7%)||5:00:12 (14%)||5:12:49 (21%)||5:25:25 (28%)|-| 4:40:00||4:53:04 (7%)||5:06:08 (15%)||5:19:12 (22%)||5:32:16 (29%)|-| 4:45:00||4:58:32 (8%)||5:12:04 (15%)||5:25:37 (23%)||5:39:09 (30%)|-| 4:50:00||5:04:01 (8%)||5:18:02 (15%)||5:32:03 (23%)||5:46:04 (31%)|-| 4:55:00||5:09:30 (8%)||5:24:00 (16%)||5:38:31 (24%)||5:53:01 (32%)|-| 5:00:00||5:15:00 (8%)||5:30:00 (16%)||5:45:00 (24%)||6:00:00 (33%)|-| 5:05:00||5:20:30 (8%)||5:36:00 (17%)||5:51:31 (25%)||6:07:01 (33%)|-| 5:10:00||5:26:01 (9%)||5:42:02 (17%)||5:58:03 (26%)||6:14:04 (34%)|-| 5:15:00||5:31:32 (9%)||5:48:04 (18%)||6:04:37 (26%)||6:21:09 (35%)|-| 5:20:00||5:37:04 (9%)||5:54:08 (18%)||6:11:12 (27%)||6:28:16 (36%)|-| 5:25:00||5:42:36 (9%)||6:00:12 (18%)||6:17:49 (28%)||6:35:25 (37%)|-| 5:30:00||5:48:09 (9%)||6:06:18 (19%)||6:24:27 (28%)||6:42:36 (38%)|-| 5:35:00||5:53:42 (10%)||6:12:24 (19%)||6:31:07 (29%)||6:49:49 (39%)|-| 5:40:00||5:59:16 (10%)||6:18:32 (20%)||6:37:48 (30%)||6:57:04 (39%)|-| 5:45:00||6:04:50 (10%)||6:24:40 (20%)||6:44:31 (30%)||7:04:21 (40%)|-| 5:50:00||6:10:25 (10%)||6:30:50 (21%)||6:51:15 (31%)||7:11:40 (41%)|-| 5:55:00||6:16:00 (11%)||6:37:00 (21%)||6:58:01 (32%)||7:19:01 (42%)|-| 6:00:00||6:21:36 (11%)||6:43:12 (21%)||7:04:48 (32%)||7:26:24 (43%)|} Example usage: You expect to run a 4:20 in 40 degree weather, but it’s going to be 70. Looking across the 4:20 line to the 70 degree column you find 4:53, which is a slowdown of 25 minutes19% reduction in performance.