Morning or evening workout? new study probes how exercise timing reshapes daily metabolism

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Women and men - with targeted recruitment to encourage females to volunteer given previous recruitment rates; anticipating fewer women than men, sex will also be included as a strata in the randomisation plan to favour the few who do volunteer being relatively evenly distributed between conditions. * A body mass index of \>18 and \<35 kg•m-2. * Minimum absolute body mass of 67 kg (to accommodate the required dose of lidocaine for 7 biopsies, plus additional for pre-incisions) * be between 18-50 years of age * Premenopausal women * Metabolically healthy (free from diagnosed metabolic illness or family history of type II diabetes * be able and willing to give informed oral and written consent, * complete and meet the defined criteria of pre-study questionnaires and screens * have a regular sleep cycle with a sleep duration between 6 and 8 h * do not exhibit extreme morning or evening preference (Horne and Ostberg, 1976) * agree to keep a constant sleep/wake cycle with a self-selected 8-h duration in bed/dark trying to sleep (from which it cannot be deviated by more than 30 minutes) for one week prior to the lab study * obtain 15 minutes of sunlight within 1.5 hours of waking up and agree to nap only within a 4 h designated nap window for one week prior to the lab study * allow confirmation of compliance to these instructions by wearing ActiHeart and light monitors continuously and complete daily sleep and event diaries for one week before the study session * agree to refrain from alcohol, caffeine, strenuous exercise and certain food components for one day before the study session * agree to weigh and record daily meals (based on individual energy requirements) for TWO days prior to the study * agree to refrain from prescribed and 'over the counter' medication and food/vitamin supplements for a wash-out period three weeks before and during the study IF the drug is deemed to affect study outcomes and may safely be withheld for that period. Exclusion Criteria: * are taking regular medication (also non-prescribed) or food supplements (e.g. vitamins, minerals, fish oil, antioxidant tablets) from which it is not possible to refrain, known to influence: sleep/alertness/the circadian timing system (e.g. beta-blockers, barbituates, antidepressants, benzodiazepines, melatonin, ritalin, modafinil, soporifics, St John's Wort), any of the metabolic functions (e.g. affecting thyroid, kidney, liver or gastrointestinal function) any of the inflammatory markers (e.g. aspirin, ibuprofen, antibiotics, hay fever medication, medication for sore throats and colds), and/or any of the endothelial markers (e.g. ACE inhibitors and angiotensin (receptor) blockers, diuretics, beta-blockers, anti-thrombosis medication), any anticoagulant medication * have a history of any circadian or sleep disorder or metabolic, cardiovascular or chronic infectious / inflammatory disease as confirmed by the GP or the pre-study questionnaires (e.g. a Pittsburgh Sleep Quality Index \> 5 will result in exclusion) * have a history of psychiatric or neurological disease or drug and alcohol abuse * have donated over 400 ml of blood in the three months preceding the study * have participated in shift work (regularly working past a typical bed time of 2300 h) or have travelled across more than two time zones within three weeks before the study * do not keep a regular sleep-wake cycle * do not refrain from alcohol, caffeine containing drinks (e.g. coffee, coke, tea, Red Bull), strenuous exercise and certain foods (e.g. those high in fat and green vegetables) for one day before and during the laboratory session * regularly consume more than 4 cups of caffeinated beverages (e.g. tea, coffee, cola) daily * smokers * have a known lidocaine allergy