Table 2.

Summary of the literature about time-of-day effects on isometric and isokinetic exercise performance.

Author(s)	Date	Protocol	Training period	Number of participants	Characteristics of the participants	Main Results (% change of peak performance time vs. other assessment time-points)	Time-of-day effect?	Peak performance time	Assessment Time-points
Aloui et al.85	2013	Maximal voluntary isometric knee extensions	—	n = 12 males	Recreationally trained soccer players	↑ 8.9% in MVC peak torque ↔ time-of-day dependent variations in MVC peak torque after 2 and 4 weeks of intermittent-fasting2 conditions	Yes	17:00–19:00 h	07:00–09:00 and 17:00–19:00 h
Callard et al.80	2000	Maximal voluntary isometric knee extensions	—	n = 6 males	Competitive cyclists	↑ 6% in MVC peak torque under resting conditions ↑ 7.8% in MVC peak torque under 24-h cycling3 conditions ↑ EMG activity at 13:00, 17:00 and 21:00 h	Yes	19:10–19:30 h*	00:01, 05:00, 09:00, 13:00, 17:00 and 21:00 h
Castaingts et al.55	2004	Electrically induced, reflex and maximal and submaximal voluntary isometric contractions	—	n = 11 males	N/A	↑ 17.6% in NME (in electrically induced contraction conditions) ↔ NME (in maximal voluntary isometric contraction conditions) throughout the day ↔ Reflex excitability throughout the day	Yes	18:00 h	06:00 and 18:00 h
Chtourou et al.30	2012	Maximal voluntary isometric knee extensions	12 weeks of training + 2 weeks of tapering at a specific time of day	n = 31males	Physical Education students	↑ 10.8% in MVC peak torque before the training period ↔ MVC peak torque throughout the day in the morning-training group after 12 weeks of training + 2 weeks of tapering at a specific time of day ↔ magnitude of MVC strength gains after 12 weeks of training + 2 weeks of tapering at a specific time of day	Yes	17:00 h	07:00 and 17:00 h
Edwards et al.76	2013	Handgrip strength, isokinetic leg strength1, and maximal voluntary isometric contractions	—	n = 10 males	Physically active and healthy adults	↑ 3.3% in grip strength performance ↑ 20.9% in isokinetic knee flexion peak torque and 18.2% in Ppeak at 1.05 rad.s(-1) ↑ 10.8% in isokinetic knee extension peak torque at 1.05 rad.s(-1) and 9.4% in isokinetic knee extension peak torque at 4.19 rad.s(-1) ↔ time-of-day dependent variations in strength and power performances even when active4 or passive5 warm-up conditions were imposed in the morning	Yes	17:30 h	07:30 and 17:30 h
Gauthier et al.77	1996	Maximal and submaximal voluntary isometric contractions at 90° of elbow flexors	—	n = 7 males n = 6 females	Physical Education students	↑ 3.94% in isometric elbow flexion peak torque at 90° ↑ NME slope throughout the day	Yes	18:00 h	06:00, 09:00, 12:00, 15:00, 18:00, 21:00 and 00:00 h
Giacomoni, Billaut and Falgairette33	2006	Maximal voluntary isometric knee extensions	—	n = 12 males	Physically active and healthy adults	↑ 2.1% in 5-min post-test EMG ↑ 14% in 5-min post-test NME (faster short-term recovery patterns of neuromuscular function)	Yes	08:00–10:00 h	08:00–10:00 and 17:00–19:00 h
Gueldich et al.78	2017	Maximal voluntary isometric knee extensions	5 weeks of training	n = 20 males	Physical Education students	↑ 3.6% and 4.3% in MVC peak torque (in the morning- and evening-training groups, respectively) before the training period ↔ EMG throughout the day ↓ 86% time-of-day dependent variations in MVC peak torque in the morning-training group after 5 weeks of training at a specific time of day	Yes	17:00 h	07:00 and 17:00 h
Guette, Godin and Martin79	2005	Plantar flexion of soleus muscle under voluntary and evoked conditions	—	n = 12 males	Physical Education students	↓ 4.9% in MVC peak torque and 18.8% in associated soleus EMG in the evening	Yes	06:00–08:00 h	06:00–08:00 and 17:00–19:00 h
Guette, Gondin and Martin26	2005	Electrically evoked and maximal voluntary isometric contractions	—	n = 10 males	Physical Education students	↑ 3.3% in MVC peak torque of the quadriceps and semi-tendinous muscles	Yes	18:18 h*	06:00, 10:00, 14:00, 18:00 and 22:00 h
Guette et al.39	2006	Percutaneous electrical stimuli and maximal voluntary isometric contraction of the plantar flexors	—	n = 11 males	Physical Education students	↓ 7% in MVC peak torque and 21% in associated soleus EMG in the evening	Yes	06:00–08:00 h	06:00–08:00 and 17:00–19:00 h
Kuusmaa, Sedliak and Hakkinen68	2015	Maximal bilateral isometric leg press, maximal unilateral isometric knee extension and maximal voluntary activation level during unilateral isometric knee extension	—	n = 72 males	Physically active and healthy adults	↑ 4.4% in MVCLP and 4.3% in MVCKE peak torque at 18:00 h ↑ 10.8% in MVCLP and 5.7% in MVCKE peak torque at 07:30 h in morning-type individuals ↑ 16.1% in MVCLP, 13.5% in MVCKE, 6.2% in MVCVA peak torque and VA% at 18:00 h in evening-type individuals ↔ MVCVA peak torque and VA% throughout the day ↔ EMGLP and EMGVA throughout the day	Yes	-	07:30 and 18:00 h
Küüsmaa-Schildt et al.69	2017	Maximal voluntary isometric knee extensions coupled with EMG recordings	24 weeks of training	n = 51 males	Physically active and healthy adults	↔ MVC peak torque, Ppeak and VA% throughout the day after 24 weeks of training at a specific time of day	No	-	06:30–09:30 and 16:30–19:30 h
Lappalainen et al.81	2009	Isokinetic leg strength (knee extension at 120°/s)	—	n = 26 males	Untrained healthy adults	↑ isokinetic peak torque at 120°/s and total work	Yes	16:30 h	08:00 and 16:30 h
Martin et al.29	1999	Electrically evoked and maximal voluntary isometric contractions	—	n = 12 males n = 1 female	Healthy adults	↑ 8.9% in MVC peak torque ↑ 9.2% in tetanic force, 18% in maximum rate of tension development and 32% in relaxation of the twitch	Yes	18:00 h	07:00 and 18:00 h
Nicolas et al.82	2005	Isokinetic leg strength6	—	n = 12 males	Physically active and healthy adults	↑ 7.7% in isokinetic peak torque ↓ 3.4–5.1% in NME of vastus lateralis, vastus medialis and rectus femoris muscles in the evening ↔ EMG throughout the day	Yes	18:00 h	06:00 and 18:00 h
Nicolas et al.70	2007	Isokinetic and isometric leg strength7	—	n = 10 males	Physically active and healthy adults	↑ 4–8.8% in MVC peak torque and isokinetic peak torque at 60, 240, 0 and −60°/s	Yes	18:00 h	06:00 and 18:00 h
Nicolas et al.34	2008	Maximal voluntary isometric knee extensions	—	n = 11 males	Competitive cyclists	↑ 6.7% in MVC peak torque and 6.8% in NME	Yes	18:00 h	06:00 and 18:00 h
Pearson and Onambele83	2005	Isokinetic leg strength8 coupled with EMG recordings and theta and patella tendon stiffness recordings	—	n = 13 males	N/A	↑ 29.4% in isokinetic knee extension peak torque at 70° ↑ 8% and 35% in vastus lateralis pennation angle in relaxed and peak contracted conditions, respectively ↓ 40% in tendon stiffness in the evening	Yes	17:45 h	07:45 and 17:45 h
Robinson et al.72	2013	Handgrip strength, isokinetic leg strength9 and maximal voluntary isometric contractions	—	n = 10 males	Physically active and healthy adults	↑ 4.3% and 7.6% in left and right handgrip strength, respectively ↑ 10.3% in MVC peak torque ↑ 12.6–16.3% in isokinetic knee flexion and extension peak torque and power at 1.05 rad.s(-1) and 8.6% in isokinetic knee extension peak torque at 4.19 rad.s(-1) ↔ time-of-day dependent variations in strength and power performances when pre-cooling11 conditions were imposed in the evening	Yes	17:30 h	07:30 and 17:30 h
Racinais et al.71	2005	Maximal and submaximal voluntary isometric knee extensions	—	n = 11 males	Physical Education students	↑ 12% in MVC peak torque and 25.4% in muscle contractility ↔ time-of-day dependent variations in strength and power performances in moderately warm and humid12 compared with neutral13 conditions	Yes	17:00–19:00	07:00–09:00 and 17:00–19:00 h
Sedliak et al.41	2008	Maximal and submaximal voluntary isometric knee extensions	—	n = 32 males	Physically active and healthy adults10	↑ 2.4–8.7% in MVC peak torque at 120°/s throughout the day	Yes	12:00–13:00, 17:00–18:00 and 20:30–21:30 h	07:00–08:00, 12:00–13:00, 17:00–18:00 and 20:30–21:30 h
Sedliak et al.66	2008	Maximal voluntary isometric knee extensions	10 weeks of training at a specific time of day	n = 34 males	Physically active and healthy adults10	↔ magnitude of MVC strength gains after 10 weeks of training at a specific time of day	No	—	09:00–16:00 h
Sedliak et al.73	2007	Maximal voluntary isometric knee extensions	10 weeks of training at a specific time of day	n = 38 males	Physically active and healthy adults10	↑ 3.3–9.2% in MVC peak torque throughout the day before the training period ↔ time-of-day dependent variations in MVC peak torque in the morning-training group after 10 weeks of training at a specific time of day	Yes	12:00, 17:00 and 20:30 h	07:00, 12:00, 17:00 and 20:30 h
Sedliak et al.65	2009	Maximal voluntary isometric knee extensions	10 weeks of time-of-day-specific resistance training	n = 24 males	Physically active and healthy adults10	↔ magnitude of MVC strength gains after 10 weeks of training at a specific time of day	No	—	09:00–16:00 h
Sedliak et al.74	2018	Maximal voluntary isometric knee extensions	11 weeks of training at a specific time of day	n = 25 males	Physically active and healthy adults10	↔ magnitude of MVC strength gains after 11 weeks of training at a specific time of day	No	—	07:30–08:30 and 16:00–17:00 h
Souissi et al.35	2010	Handgrip strength	—	n = 20 males	Untrained healthy boys	↑ 5.9% in handgrip strength throughout the day	Yes	14:00 and 18:00 h	08:00, 14:00 and 18:00 h
Souissi et al.36	2012	Maximal voluntary isometric knee extensions	6 weeks of training at a specific time of day	n = 24 males	Untrained healthy boys	↑ 8.4% in MVC peak torque before the training period. ↔ time-of-day dependent variations in MVC peak torque in the morning-training group after 6 weeks of training at a specific time of day	Yes	17:00–18:00 h	07:00–08:00 and 17:00–18:00 h
Souissi et al.54	2002	Isokinetic leg strength at six angular velocities (1.05, 2.10, 3.14, 4.19, 5.24 and 6.29 rad.s(-1))	6 weeks of training at a specific time of day	n = 14 males	Physical Education students	↑ isokinetic knee extension peak torque at 17:00–18:00 h before the training period. ↔ time-of-day dependent variations in isokinetic knee extension peak torque in the morning-training group after 6 weeks of training at a specific time of day ↑ 38.6% in absolute levels of isometric knee extension peak torque at 07:00–08:00 h in the morning-training group after 6 weeks of training at a specific time of day ↑ 21.2% in absolute levels of isometric knee extension peak torque at 17:00–18:00 h in the evening-training group after 6 weeks of training at a specific time of day	Yes	—	07:00–08:00 and 17:00–18:00 h
Tamm et al.75	2009	Magnetic stimulation of the cortex, electrical stimulation of the tibial nerve and maximal isometric contractions of the triceps surae muscles	—	n = 16 males n = 7 females	Untrained healthy adults	↑ cortical excitability at 09:00 h in morning-type individuals ↑ cortical excitability at 21:00 h in evening type-individuals ↔ spinal excitability throughout the day in morning- nor evening-type individuals ↔ MVC peak torque nor EMG throughout the day in morning-type individuals. ↑ 13% in MVC peak torque and 23% in EMG throughout the day in evening-type individuals	Yes	—	09:00, 13:00, 17:00 and 21:00 h
Wyse et al.84	1994	Isokinetic leg strength14	—	n = 9 males	Collegiate sportsmen adults	↑ 5–12% in isokinetic peak torque of knee flexors and extensors at 1.05 and 3.14 rad.s(-1)	Yes	18:00–19:30 h	08:00–09:00, 13:00–14:00 and 18:00–19:30 h
Zbidi et al.45	2016	Maximal voluntary isometric contractions of the elbow flexors and extensors	6 weeks of training at a specific time of day	n = 20 males	Physical Education students	↑ 5.9% and 6.5% in MVF and MRFD, respectively, before the training period ↔ time-of-day dependent variations in MVF and MRFD in the morning-training group after 6 weeks of training at a specific time of day	Yes	17:00–18:00 h	07:00–08:00 and 17:00–18:00 h

EMG electromyographic activity, MCV maximal voluntary contraction, NME Neuromuscular efficiency (mechanical performances/EMG recordings), N/A Not available, ¹ i.e. knee flexion and extension at 1.05 and 4.19 rad.s(-1) through a 90° range of motion ² i.e. 15–16 h starvation/day; from ≈ 04:00 h till ≈ 19:00 h, ³ i.e. 24-h cycling on an indoor trainer with minimal resting periods at a submaximal work rate (paced speed set at 70% of the subject’s maximal aerobic speed, corresponding approximately to 50% of their maximal aerobic power) ⁴i.e. 20–40 min of pedaling on a cycle ergometer at 150 W, ⁵i.e. 45–65 min of resting in a room at 35 °C, 45% relative humidity, ^*estimated acrophase by cosinor analysis.

EMG electromyographic activity, MCV maximal voluntary contraction, NME Neuromuscular efficiency (mechanical performances/EMG recordings), MVCLP maximal bilateral isometric leg press, EMGLP myoelectric activity during maximal bilateral isometric leg press, MVCKE maximal unilateral isometric knee extension, MVCVA maximal voluntary activation level unilateral isometric knee extension, EMGVA myoelectric activity during maximal voluntary activation level unilateral isometric knee extension, VA% voluntary activation percentage of the quadriceps muscles, ^*estimated acrophase by cosinor analysis.

EMG electromyographic activity, MCV maximal voluntary contraction, NME Neuromuscular efficiency (mechanical performances/EMG recordings), N/A Not available, ⁶i.e. knee extension at 2.09 rad.s(-1) through a 90° range of motion, ⁷ i.e. knee flexion at 240°/s, 60°/s, 0°/s, −60°/s, ⁸i.e. knee flexion and extension at 90°/s, 80°/s, 70°/s, 50°/s and 30°/s, ⁹ i.e. knee flexion and extension at 1.05 and 4.19 rad.s(-1) through a 90° range of motion, ¹⁰ i.e. no medication within the last14 days, a non-smoker, regular sleep pattern with sleep duration ranging from 6 to 9 h per night and regular physical activity not more than once a week, ¹¹¹ i.e. immersion in cold water (16.5 °C) before testing to lower rectal temperature to morning values, ¹²i.e. 60 min of resting in a room at 29.5 °C, 74% relative humidity, ¹³ i.e. 60 min of resting in a room at 20.5 °C, 67% relative humidity.

EMG electromyographic activity, MCV maximal voluntary contraction, ¹⁰i.e. no medication within the last14 days, a non-smoker, regular sleep pattern with sleep duration ranging from 6 to 9 h per night and regular physical activity not more than once a week.

MVF maximal voluntary force, MRFD maximal rate of force development, ¹⁴i.e. knee flexion and extension at 1.05 and 3.14 rad.s(-1) through a 90° range of motion.