Darryl J McAndrew

Review of anatomy education in Australian and New Zealand medical schools

Anatomy instruction at Australian and New Zealand medical schools has been the subject of considerable debate recently. Many commentators have lamented the gradual devaluation of anatomy as core knowledge in medical courses. To date, much of this debate has been speculative or anecdotal and lacking reliable supporting data. To provide a basis for better understanding and more informed discussion, this study analyses how anatomy is currently taught and assessed in Australian and New Zealand medical schools.

The effect of a familiarisation period on subsequent strength gain

Abstract Untrained subjects can display diverse strength gain following an identical period of resistance exercise. In this investigation, 28 untrained males completed 16-weeks of resistance exercise, comprising 4-weeks familiarisation, and 12-weeks of heavy-load (80–85%) activity. High and low responders were identified by the Δ1RM (Δ one repetition maximum) observed following familiarisation (25.1 ± 1.4%, 9.5 ± 1.4%, P < 0.0001) and differences in electromyographic root mean square amplitude (ΔEMGRMS 29.5 ± 8.3%, 2.4 ± 6.0%, P = 0.0140), and habitual and occupational activity patterns were observed between these respective groups. The strength gain (P < 0.0001) observed within high (29.6 ± 1.7%) and low (31.4 ± 2.7%) responding groups was similar during the heavy-load phase, yet ΔEMGRMS increased (P = 0.0048) only in low responders (31.5 ± 9.3%). Retrospectively, differences (P < 0.0001) in baseline 1RM strength of high- (19.7 ± 0.9 kg) and low-responding (15.6 ± 0.7 kg) groups were identified, and a strong negative correlation with Δ1RM after 16-weeks (r 2 = −0.85) was observed. As such, baseline 1RM strength provided a strong predicative measure of strength adaptation. The ΔEMGRMS suggests strength variability within high and low responders may be attributed to neural adaptation. However, differences in habitual endurance and occupational physical activity suggests one should consider screening not only recent resistance training, but also other modes of physical activity during participant recruitment.

MUSCLES WITHIN MUSCLES: THE CLASSICAL TRIPHASIC EMG BURST AND ITS APPLICABILITY TO SEGMENTS OF LARGE RADIATE AGONIST/ANTAGONIST MUSCLES

The purpose of the current study was to determine if the classically described triphasic EMG burst was applicable in describing the EMG patterns across the breadth of three large radiate muscles during the production of a rapid shoulder joint movement. Miniature (6.5 mm inter-electrode distance) bipolar surface electrodes were placed across the breadth of the pectoralis major (6 off), latissimus dorsi (6 off) and the deltoid (7 off). Subjects performed a series of rapid shoulder joint adduction movements (<400 ms) against the resistance of a free weight and pulley apparatus whilst seated in an experimental chair. EMG data sampled from the multiple recording sites of the three muscles identified four different types of EMG waveforms. This was based on the presence, or absence, of multiple bursts, the length of each burst and the level of the silent period between bursts from the same segment of a muscle. The four bursts included a one-burst pattern, a one-continuous burst pattern, a two-continuous burst pattern and a two non-continuous burst pattern. Upon further analysis it was established that a relationship existed between the type of burst displayed by a segment and the functional role of that segment (prime mover, synergist, primary or secondary antagonist), hence a uniform type of burst pattern was not apparent across the breadth of the agonist (pectoralis major and latissimus dorsi) and antagonist (deltoid) muscles. It was evident that the triphasic EMG burst was most applicable for the EMG patterns arising from the prime mover segments of the pectoralis major and the latissimus dorsi and the primary antagonist segment of the deltoid. In conclusion, these results suggest that caution is warranted if stating that popular motor control theories10, 11 based on EMG patterns produced by small agonist and antagonist muscles during rapid limb movement, apply to all segments of large radiate muscles.

Of mice, pigs and humans: An analysis of mitochondrial phospholipids from mammals with very different maximal lifespans.

The maximal lifespan (MLS) of mammals is inversely correlated with the peroxidation index, a measure of the proportion and level of unsaturation of polyunsaturated fatty acids (PUFA) in membranes. This relationship is likely related to the fact that PUFA are highly susceptible to damage by peroxidation. Previous comparative work has examined membrane composition at the level of fatty acids, and relatively little is known regarding the distribution of PUFA across phospholipid classes or phospholipid molecules. In addition, data for humans is extremely rare in this area. Here we present the first shotgun lipidomics analysis of mitochondrial membranes and the peroxidation index of skeletal muscle, liver, and brain in three mammals that span the range of mammalian longevity. The species compared were mice (MLS of 4 years), pigs (MLS of 27 years), and humans (MLS of 122 years). Mouse mitochondria contained highly unsaturated PUFA in all phospholipid classes. Human mitochondria had lower PUFA content and a lower degree of unsaturation of PUFA. Pig mitochondria shared characteristics of both mice and humans. We found that membrane susceptibility to peroxidation was primarily determined by a limited number of phospholipid molecules that differed between both tissues and species.

The impact of contraction velocity on amortisation and electromyographic activity during heavy-load resistance exercise

Heavy-load resistance exercise is not normally associated with stretch shortening muscle activation. Rapid lengthening, and a decreased period of time between lengthening and shortening phases of contraction (amortisation phase) has been associated with increased energy transfer from passive muscle structures (series elastic component, SEC), and gains in muscle efficiency during stretch shortening muscle activation. In this investigation, we sought to determine the effect of limb velocity on the amortisation phase and electromyographic (EMG) activity during heavy load (85%1RM) resistance exercise. Twelve healthy males performed 6RM unilateral elbow flexion-extension exercise during; rapid lengthening-shortening, rapid shortening and slow lengthening-shortening muscle activation. The amortisation phase and velocity of lengthening and shortening were determined using a shaft encoder and muscle activity was recorded at the biceps brachii using intramuscular and surface EMG. A decrease (P<0.05) in time spent in amortisation was observed during rapid lengthening-shortening (0.10±0.00 ms), compared to rapid shortening (0.14±0.00 ms) and slow lengthening-shortening (0.19±0.00 ms). Intramuscular EMG was ∼25% (P<0.05) greater during the first, second and third repetition of rapid lengthening-shortening exercise compared to the other two conditions. A trend towards increased surface EMG activity was also noted during rapid lengthening-shortening, however significance (P<0.05) was only observed in the second repetition. In this investigation, the characteristics typical of a stretch shortening muscle activation were observed alongside elevated electromyographic activity during heavy-load rapid lengthening-shortening resistance exercise.