This study investigated the effect of strength training, endurance training, and combined strength plus endurance training on fibre-type transitions, fibre cross-sectional area (CSA) and MHC isoform content of the vastus lateralis muscle. Forty volunteers (24 males and 16 females) were randomly assigned to one of four groups: control (C), endurance training (E), strength training (S), or concurrent strength and endurance training (SE). The S and E groups each trained three times a week for 12 weeks; the SE group performed the same S and E training on alternate days. The development of knee extensor muscle strength was S>SE>E ( P<0.05) and has been reported elsewhere. The reduction in knee extensor strength development in SE as compared to S corresponded to a 6% increase in MHCIIa content ( P<0.05) in SE at the expense of the faster MHCIId(x) isoform ( P<0.05), as determined by electrophoretic analyses; reductions in MHCIId/x content after S or E training were attenuated by comparison. Both S and SE induced three- to fourfold reductions ( P<0.05) in the proportion of type IIA/IID(X) hybrid fibres. S also induced fourfold increases in the proportion of type I/IIA hybrid fibres within both genders, and in a population of fibres expressing a type I/IID(X) hybrid phenotype within the male subjects. Type I/IIA hybrid fibres were not detected after SE. Both S and SE training paradigms induced similar increases (16-19%, P<0.05) in the CSA of type IIA fibres. In contrast, the increase in CSA of type I fibres was 2.9-fold greater ( P<0.05) in S as compared to SE after 12 weeks. We conclude that the interference of knee extensor strength development in SE versus S was related to greater fast-to-slow fibre-type transitions and attenuated hypertrophy of type I fibres. Data are given as mean (SEM) unless otherwise stated.

This paper presents a compact dual-band dualpolarized microstrip antenna array with wide bandwidth and low profile for multiple-input multiple-output (MIMO) synthetic aperture radar-imagery applications where both high resolution and portability are required. This array has a stacked structure, consisting of two shared-aperture dual-band orthogonalpolarized sub-arrays with high isolation. Each pair of driven patches for the two-band shares two parasitic patches to achieve compactness. Slits are etched on the shared parasitic patches to adjust the coupling frequency between two elements of the two bands. The defected ground structure integrated in the array effectively suppresses H-plane cross-polarization. A 4 × 6 array as an MIMO element sized of 77 mm × 79 mm × 2.2 mm has been fabricated and tested. Both wide beamwidth and stable gain are achieved, where the impedance bandwidth of 27.7%, 30.6%, 15.6%, and 23.8% in X-band vertical, X-band horizontal, Ku-band vertical, and Ku-band horizontal polarizations, respectively.

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