What the experts say
Nigel Hetherington reviews the latest research material relating to coaching, exercise physiology and athletic development.
Different pacing strategies for 11 female 5km runners were examined. Two preliminary 5km treadmill time trials were recorded to 'baseline' the study. From this, the pace for the first 1.63km (1mile) in subsequent runs was either as per the preliminary run pace (even), 3% faster or 6% faster. Ventilation, O2max and other physiological parameters were measured continuously. Average times were 21:11, 20:52 and 20:39 for even pace, 3% and 6% faster paces respectively and physiological factors were not significantly different between the 3% and 6% faster efforts in the first 1.63km. The fastest overall times for eight subjects came from the 6% faster efforts in this first stage. Based on this research the first 1.63km of a 5km race can be completed between 3% and 6% faster than the current average race pace without negatively affecting performance. Indeed, in order to optimise performance runners should start the initial 1.63km at this elevated pace.
Research sought to compare critical velocity (CV, theoretically, the highest velocity that can be sustained without fatigue) calculated from different mathematical models to determine which correlated best with 1-hour performance and which method provided the most accurate prediction of performance. Twelve male endurance runners performed three constant duration tests (6, 9, and 12 minutes), a maximal running velocity test (to estimate CV) and a 1-hour track test. Calculations for estimated CV and the highest velocity that could be sustained for 1 hour were made. Analysis of actual and predicted performance revealed that none of the models provided an accurate prediction of the 1-hour performance velocity. Estimation of CV allows endurance runners to be ranked on long-distance running performance, but no model provides an accurate prediction of actual performance of use to coaches or athletes.
10 weeks of creatine monohydrate (Cr) supplementation coupled with resistance training on body composition and strength in women has been examined. Twenty-six subjects ingested Cr (0.3 g·kg-1 body mass) or a placebo (Pl) for 1 week and then during 9 weeks of resistance training. Significant increases occurred in both groups for lean body mass and 1RM bench press and incline leg press. There was no significant difference in the total number of repetitions completed after five sets of multiple repetitions to exhaustion at 70% of 1RM for bench press and incline leg press for both groups or in the ability to perform a greater training volume in the Cr vs. Pl groups over the 10 weeks. The results indicate that Cr supplementation combined with 10 weeks of concurrent resistance training may not improve strength or lean body mass greater than training only. These findings may be a result of non-responders due to gender differences or a varying biological potential to uptake Cr within the muscle.
Researchers aimed to assess if an acute caffeine dose could enhance agility and anaerobic power. Sixteen recreationally active young adult males who were not habituated to caffeine performed the pro-agility run and the 30-second Wingate test 60 minutes after ingestion of caffeine (6 mg·kg-1) or placebo. No significant change was observed in the pro-agility run after caffeine ingestion compared with placebo. In addition, no significant change was observed in peak power, mean power, or per cent power decrease. The effects of daily administration of a caffeine-containing supplement in conjunction with 8 weeks of aerobic training on O2peak, time to running exhaustion at 90% O2peak, body weight, and body composition were studied. Thirty-six college students ingested one dose of the placebo or supplement (201mg caffeine) per day during the study period. The subjects also performed treadmill running for 45 minutes at 75% of the heart rate at O2peak, three times per week for 8 weeks. All subjects were tested both pre-training and post-training for O2peak, time to running exhaustion (TRE) at 90% O2peak, body weight (BW), percentage body fat (%FAT), fat weight (FW), and fat-free weight (FFW). The results indicated that there were equivalent training-induced increases in O2peak and TRE for the supplement and placebo groups, but no changes in BW, %FAT, FW, or FFW for either group. These findings indicated that chronic use of the caffeine-containing supplement in the present study, in conjunction with aerobic training, provided no ergogenic effects as measured by O2peak and TRE, and the supplement had any effect on body weight or composition.
A paper reviewing factors affecting rest interval between resistance sets examined the premise that 'multiple sets are superior to single sets for maximal strength development'. Whether maximal strength gains are achieved may depend on the ability to sustain a consistent number of repetitions over consecutive sets, which may be impacted on by the rest interval between sets. The length of the rest interval is prescribed based on the training goal but may vary based on several other factors. When training for muscular strength, the magnitude of the load lifted is a key determinant of the between-set rest interval. For loads, less than 90% of 1RM, 3-5 minutes rest between sets allows for greater strength increases through the maintenance of training intensity. However, when testing for maximal strength, 1-2 minutes rest between sets might be sufficient between repeated attempts. When training for muscular power, a minimum of 3 minutes rest should be taken between sets of repeated maximal effort movements (e.g. plyometric jumps). When training for muscular hypertrophy, consecutive sets should be performed prior to when full recovery has taken place. Shorter rest intervals of 30-60 seconds between sets have been associated with higher acute increases in growth hormone, which may contribute to the hypertrophic effect. When training for muscular endurance, an ideal strategy might be to perform resistance exercises in a circuit, with shorter rest intervals (e.g. 30 seconds) between exercises that involve dissimilar muscle groups, and longer rest intervals (e.g., 3 minutes) between exercises that involve similar muscle groups. In summary, the length of the rest interval between sets is only 1 component of a resistance exercise program directed toward different training goals. Prescribing the appropriate rest interval does not ensure the desired outcome if other components such as intensity and volume are not prescribed appropriately.
A study aimed to determine whether a significant strength imbalance existed between the left and right or dominant (D) and non-dominant (ND) legs and to investigate possible correlations between a field and laboratory tests to determine strength imbalance. Fourteen collegiate women softball players underwent measures of average peak torque for isokinetic flexion and extension at 60°·s-1 and 240°·s-1; in addition, measures of peak and average force of each leg during parallel back squat, 2-legged vertical jump, and single-leg vertical jump and performance in a 5-hop test were examined. Significant differences of between 4.2% and 16.0% were evident for all measures except for average force during single-leg vertical jump between the D and ND limbs, thus revealing a significant strength imbalance. The 5-hop test revealed a significant difference between D and ND limbs and showed a moderate correlation with laboratory tests, suggesting potential use as a field test for strength imbalance. A significant strength imbalance can exist even in collegiate level athletes.
Research has assessed the effect of stable vs. unstable conditions on force output and muscle activity during an isometric squat. Nine recreationally resistance trained men completing a single testing session. Subjects performed isometric squats either standing on the force plate (stable condition, S) or standing on inflatable balls on the force plate (unstable condition, U). Electromyography (EMG) was recorded from the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and medial gastrocnemius (G) muscles. Peak force (PF) and rate of force development (RFD) were significantly lower in the U vs. S condition. EMG values for the VL and VM were significantly higher in the S vs. U condition. VL and VM muscle activity were less in U in comparison to S. No significant differences were observed in muscle activity of the BF or G between U and S. Isometric squatting in an unstable condition significantly reduces peak force, the rate of force development, and agonist muscle activity with no change in antagonist or synergist muscle activity. In terms of providing a stimulus for strength gain, no discernible benefit of performing a resistance exercise in an unstable condition is supported. The Swiss ball is widely used in the training environment as a supplement to conventional resistance training. An example is to use the Swiss ball as a bench support for bench press exercise.
A study investigated muscle activity using surface electromyography of upper-body and abdominal muscles during the concentric and eccentric phases of the bench-press on and off a Swiss ball. Fourteen resistance-trained subjects performed isolated bench press repetitions using the two test surfaces with a 2-second cadence at a load equivalent to 60% maximum force output. The results showed that deltoid and abdominal muscle activity was increased for repetitions performed using the Swiss ball. Increased deltoid muscle activity supports previous findings for increased activity when greater instability is introduced to the bench press movement. Abdominal muscle activity increases were not hypothesized, but this finding provides scientific evidence for the anecdotal reasoning behind Swiss ball use as a potential core stability-training device. These findings should be contrasted with those of the previous paper. In addition, surface electromyography may not respond to muscle activity associated with the muscles deeper within the abdomen responsible for core strength.
The relationship between per cent 1RM and the number of repetitions performed remains poorly studied, especially using free weight exercises. A study aimed to determine the maximal number of repetitions that trained (T), untrained (UT) men can perform during free weight exercises at various percentages of 1RM. Eight T, and UT men were tested for 1RM strength. Then, subjects performed one set to failure at 60, 80, and 90% of 1RM in the back squat, bench press, and arm curl. More repetitions were performed during the back squat than the bench press or arm curl at 60% 1RM for T and UT. At 80 and 90% 1RM, there were still significant differences between the back squat and other exercises. No differences in the number of repetitions performed at a given exercise intensity were noted between T and UT (except during bench press at 90% 1RM). The number of repetitions performed at a given per cent of 1RM is influenced by the amount of muscle mass used during the exercise, as more repetitions can be performed during the back squat than either the bench press or arm curl.
A study determined the impact of a very slow (VS) velocity versus a self-selected volitional (VOL) velocity at varying intensities on repetition number, peak force, peak power, and total volume in the squat and shoulder press exercises. On separate testing days, 9 resistance-trained men performed a squat (SQ) and shoulder press (SP) exercise at 60 or 80% of 1 repetition maximum (1RM) at either VOL or VS (10-second eccentric and 10-second concentric actions) velocity for as many repetitions as possible. Force, power, and volume (repetitions × kg) were also determined. Subjects performed significantly fewer repetitions in the VS exercises in both the SQ and the SP. Peak force and power were significantly higher at the VOL speed. VOL speed elicited higher total volume than the VS velocity. The results of the study indicate that a VS velocity may not elicit appropriate levels of force, power, or volume to optimize strength and athletic performance.
Highly trained distance runners were assigned to a plyometric (PLY) or control (CON) group. In addition to their normal training, the PLY group undertook 3 × 30 minutes PLY sessions per week for 9 weeks. Running economy (RE) was assessed during 3 × 4-minute treadmill runs (14, 16, and 18 km·h-1), followed by an incremental test to measure O2max. Muscle power was assessed on a force plate. Compared with CON, PLY improved RE at 18 km·h-1 by 4.1%, but not at 14 or 16 km·h-1. This was accompanied by trends for a 15% increase in average power during a 5-jump plyometric test, a 14% shorter time to reach maximal dynamic strength during a strength assessment test, and a 14% lower O2-speed slope after 9 weeks of PLY. There were no significant differences in cardiorespiratory measures or O2max because of PLY. In a group of highly trained distance runners, 9 weeks of PLY improved RE, with mechanisms residing in the muscle or by improving running mechanics.
The effects of sprint running training on sloping surfaces (3°) on selected kinematic and physiological variables have been studied. Thirty-five students were split into four training groups (uphill-downhill, downhill, uphill, and horizontal) and a control group. Pre- and post-training tests were performed to determine the effects of 6-weeks training on the maximum running speed at 35m, step rate, step length, step time, contact time, the eccentric and concentric phase of contact time, flight time, selected posture characteristics of the step cycle, and peak anaerobic power performance. Maximum running speed and step rate were increased significantly in a 35m running test after training by 0.29 m·s-1 (3.5%) and 0.14 Hz (3.4%) for the combined uphill-downhill group and by 0.09 m·s-1 (1.1%) and 0.03 Hz (2.4%) for the downhill group, whereas flight time shortened only for the combined uphill-downhill training group by 6 milliseconds (4.3%). There were no significant changes in the horizontal and control groups. Posture characteristics and peak anaerobic power were unaffected. It was suggested that the novel combined uphill-downhill training method is significantly more effective in improving the maximum running velocity at 35m and the horizontal kinematics of sprint running than other methods.
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About the Author
Nigel Hetherington was the Head Track & Field Coach at the internationally acclaimed Singapore Sports School. He is a former National Performance Development Manager for Scottish Athletics and National Sprints Coach for Wales. Qualified and highly active as a British Athletics level 4 performance coach in all events he has coached athletes to National and International honours in sprints, hurdles as well as a World Record holder in the Paralympic shot. He has 10 years' experience as senior coach educator and assessor trainer on behalf of British Athletics. Nigel is also an experienced athlete in sprint (World Masters Championship level) and endurance (3-hour marathon runner plus completed the 24 hour 'Bob Graham Round' ultra-endurance event up and down 42 mountain peaks in the English Lake District). He is a chartered chemist with 26 years' experience in scientific research and publishing.
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