Research into human tendon properties by Costis Maganaris, Vassilios Baltzopolous and Anthony J Sargeant


Changes in Achilles tendon moment arm from rest to maximum isometric plantarflexion: In vivo observations in man

Article (PDF Available)inThe Journal of Physiology 510 ( Pt 3)(3):977-85 · August 1998with85 Reads

DOI: 10.1111/j.1469-7793.1998.977bj.x · Source: PubMed
  • 35.76 · Liverpool John Moores University
  • 38.82 · Liverpool John Moores University
  • 41.33 · VU University Amsterdam
    1. The purpose of the present study was to examine the effect of a plantarflexor maximum voluntary contraction (MVC) on Achilles tendon moment arm length.
    2. Sagittal magnetic resonance (MR) images of the right ankle were taken in six subjects both at rest and during a plantarflexor MVC in the supine position at a knee angle of 90 deg and at ankle angles of -30 deg (dorsiflexed direction), -15 deg, 0 deg (neutral ankle position), +15 deg (plantarflexed direction), +30 deg and +45 deg. A system of mechanical stops, support triangles and velcro straps was used to secure the subject in the above positions. Location of a moving centre of rotation was calculated for ankle rotations from -30 to 0 deg, -15 to +15 deg, 0 to +30 deg and +15 to +45 deg. All instant centres of rotation were calculated both at rest and during MVC. Achilles tendon moment arms were measured at ankle angles of -15, 0, +15 and +30 deg.
    3. At any given ankle angle, Achilles tendon moment arm length during MVC increased by 1-1.5 cm (22-27 %, P < 0.01) compared with rest. This was attributed to a displacement of both Achilles tendon by 0.6-1.1 cm (P < 0.01) and all instant centres of rotation by about 0.3 cm (P < 0.05) away from their corresponding resting positions.
    4. The findings of this study have important implications for estimating loads in the musculoskeletal system. Substantially unrealistic Achilles tendon forces and moments generated around the ankle joint during a plantarflexor MVC would be calculated using resting Achilles tendon moment arm measurements.

    Changes in Achilles tendon moment arm from rest to maximum isometric plantarflexion: In vivo observations in man (PDF Download Available). Available from: [accessed May 1, 2017].

Functional and structural changes after disuse of human muscle – first study to quantify disuse muscle atrophy at fibre level in humans


Clinical Science and Molecular Medicine (1977) 52, 337-342. Functional and structural changes after disuse of human muscle – Authors: ANTHONY J SARGEANT,* C. T. M. DAVIES,* R. H. T. EDWARDS, C. MAUNDER AND A. YOUNG *Medical Research Council Environmental Physiology Unit, London School of Hygiene and Tropical Medicine, University of London, and Jerry Lewis Muscle Research Centre, Royal Postgraduate Medical School, Hammersmith Hospital, London


1. Seven patients who had suffered unilateral leg fracture were studied after removal of immobilizing plaster casts.

2. Leg volume measured anthropometrically was reduced by 12% in the injured leg (5.68 f 1.05 litres) compared with the uninjured (6.43 f 0.87 litres). Associated with this loss was a similar reduction in the net maximum oxygen uptake achieved in one-leg cycling, from 1.89 k 0.21 l/min in the uninjured leg to 1.57+0.18 l/min in the injured.

3. Measured by a percutaneous needle biopsy technique, a reduction of 42% was found in the cross-sectional area of the muscle fibres sampled from the vastus lateralis of the injured compared with the uninjured leg.

4. Staining for myosin adenosine triphosphatase activity showed that both type I and I1 fibres were affected, being reduced respectively from 3410 to 1840 pm2 and from 3810 to 2390 pm2 cross-sectional area.

5. Possible reasons and implications are discussed for the discrepancy between the magnitude of the difference observed in the gross measurement of leg function (maximum oxygen uptake) and structure (leg volume) as compared with the cellular level (cross-sectional fibre area).


Correspondence: Dr A. J. Sargeant, MRC Environmental Physiology Unit, London School of Hygiene and Tropical Medicine, University of London, Keppel Street (Gower Street), London WClE 7HT.


Atrophy of the affected limb and loss of muscle power follows bone fracture and subsequent immobilization. Years of experience have enabled the rehabilitation professions to develop empirical programmes to reverse these changes. However, the efficacy of such programmes may be further improved if we can increase our understanding of the atrophic response to disuse in human muscle. Recent studies showed that 15 weeks immobilization in a long-leg plaster cast after fracture reduced the fat-free volume of the affected leg by 12%, which was accompanied by a similar fall in the maximum oxygen uptake ( ~oz,,,,=.) achieved with oneleg pedalling (Davies & Sargeant, 1975a,b). However, it was not known how far these changes in gross structure and function were reflected at a cellular level within the affected muscles. Since the work of pedalling is performed mainly by the leg extensors (A. J. Sargeant & C. T. M. Davies, unpublished work) needle biopsy was used (Edwards, Maunder, Lewis & Pearse, 1973) to study fibre atrophy in the quadriceps femoris muscle and to compare this with measurements of the gross leg volume and maximal oxygen uptake of patients recovering from unilateral leg fracture.

Regional variation in recruitment and physiological properties of a single muscle


This research published in the Journal of Neurophysiology was carried out in Amsterdam by Jo De Ruiter as part of his doctoral thesis supervised by Professor Anthony J Sargeant and Arnold de Haan. It was part of a series of studies examining the regional differences within a single muscle of physiological properties and hence pattern of recruitment in response to different intensities of exercise.

Fast-twitch muscle unit properties in different rat medial gastrocnemius muscle compartments

DeRuiter CJArnold de HaanAnthony J Sargeant.

Journal of Neurophysiology
J Neurophysiol. 1996 Jun;75(6):2243-54
  • 1. The effect of muscle unit (MU) localization on physiological properties was investigated within the fast-twitch fatigue-resistant (FR) and fast-fatigable (FF) MU populations of rat medial gastrocnemius (MG) muscle. Single MG MUs were functionally isolated by microdissection of the ventral roots. FR and FF MU properties of the most proximal and distal muscle compartments were compared. The most proximal and distal compartment are subvolumes of the MG innervated by the most proximal and distal primary nerve branch, respectively. A subsample of the isolated units was glycogen depleted and muscle cross sections were stained for glycogen and myosin-adenosinetriphosphatase.
  • 2. It was shown that proximal FF and FR units reached optimum length for force production at shorter muscle lengths compared with the distal FR and FF units.
  • 3. The fast MUs of the proximal compartment had small territories that were located close to and/or within the mixed region (containing type I, IIA, IIX, and IIB fibers) of the muscle. The fast MUs of the distal compartment had greater territories that were located in the more superficial muscle part (containing only type IIX and IIB fibers) and in some cases spanned the entire area of the distal muscle compartment.
  • 4. FR and FF MUs consisted of muscle fibers identified histochemically as type IIX and IIB, respectively.
  • 5. Within each of the FR and FF MU populations, MUs that were located in the most proximal muscle compartment were more resistant to fatigue compared with the units located in the most distal compartment.
  • 6. Cross-sectional fiber areas were smaller for the proximal FR and FF fibers, but specific force did not differ among units. Consequently, when account was taken of the innervation ratio, the proximal FR and FF units produced less force than distal units of the same type. Tetanic forces were 87 +/- 27 (SD) mN (proximal FR), 154 +/- 53 (SD) mN (distal FR), 142 +/- 25 (SD) mN (proximal FF), and 229 +/- 86 (SD) mN (distal FF).
  • 7. The present findings suggest that with increasing demand placed on rat MG during in vivo locomotion, recruitment is likely to proceed from proximal to distal muscle parts within the FR and FF MU populations.

Within a single muscle there can be large differences in fatiguability and other physiological properties


This research carried out in Amsterdam under the direction of Professor Anthony J Sargeant demonstrated how within the same anatomical muscle there can be quiet different physiological properties in different areas of the same muscle. This work was part of the PhD research of Jo de Ruiter supervised by Professor Tony Sargeant and Arnold de Haan.

Repeated force production and metabolites in two medial gastrocnemius muscle compartments of the rats

De Ruiter CJArnold de HaanAnthony J Sargeant.

Journal of Applied Physiology
J Appl Physiol. 1995 Dec;79(6):1855-61
  • The most proximal and distal motor nerve branches in the rat medial gastrocnemius innervate discrete muscle compartments dominated by fast-twitch oxidative and fast-twitch glycolytic fibers, respectively. The functional consequences of the difference in oxidative capacity between these compartments were investigated. Wistar rats were anesthetized with pentobarbital sodium (90 mg/kg ip). Changes in force of both compartments during 21 isometric contractions (train duration 200 ms, stimulation frequency 120 Hz, 3 s between contractions) were studied in situ with and without blood flow. Without blood flow, force and phosphocreatine declined to a greater extent in the proximal than the distal compartment compared with the run with intact flow. After the protocol without blood flow, when flow was restored, the time constants for force recovery (which were closely associated to the recovery of phosphocreatine) were 37 +/- 7 (SD) (proximal compartment) and 148 +/- 20 s (distal compartment). It was concluded that the proximal compartment had a four times higher oxidative capacity and, therefore, a superior ability for repeated force production.

Human Muscle Power


The ability of generating muscle power power is important whether you are an Olympic athlete, a ballet dancer, or an elderly person wanting to climb the stairs to go to bed. In this comprehensive review of his research Anthony Sargeant points out the importance of different types of muscle fibres that make up the human skeletal muscles that produce power in legs and arms. Tony also points out that in research seeking to measure human muscle power it is essential to measure or control the speed at which the power is generated (this is because power is the product of work and velocity).

Structural and functional determinants of human muscle power
by Anthony J Sargeant

Experimental Physiology
Exp Physiol. 2007 Mar;92(2):323-31

Measurements of human power need to be interpreted in relation to the movement frequency, since that will determine the velocity of contraction of the active muscle and hence the power available according to the power-velocity relationship. Techniques are described which enable movement frequency to be kept constant during human exercise under different conditions. Combined with microdissection and analysis of muscle fibre fragments from needle biopsies obtained pre- and postexercise we have been able ‘to take the muscle apart’, having measured the power output, including the effect of fatigue, under conditions of constant movement frequency. We have shown that fatigue may be the consequence of a metabolic challenge to a relatively small population of fast fatigue-sensitive fibres, as indicated by [ATP] depletion to approximately 30% of resting values in those fibres expressing myosin heavy chain isoform IIX after just 10 s of maximal dynamic exercise. Since these same fibres will have a high maximal velocity of contraction, they also make a disproportionate contribution to power output in relation to their number, especially at faster movement rates. The microdissection technique can also be used to measure phosphocreatine concentration ([PCr]), which is an exquisitely sensitive indicator of muscle fibre activity; thus, in just seven brief maximal contractions [PCr] is depleted to levels < 50% of rest in all muscle fibre types. The technique has been applied to study exercise at different intensities, and to compare recruitment in lengthening, shortening and isometric contractions, thus yielding new information on patterns of recruitment, energy turnover and efficiency.

Anthony J Sargeant

New research technique for studying human muscle fibre types – In memoriam Jose Sant’ana Pereira a highly talented but troubled scientist


This paper describes the combination of a number of complementary techniques applied to the characterisation of human muscle fibre types using microdissection of fragments of fibres obtained by needle biopsy. The work was a collaboration between the Amsterdam Research Groups directed by Professors Anthony Sargeant and Anton Moorman and that of Professor Geoffrey Goldspink in London. The work was submitted by Jose Sant’ana Pereira as part of his PhD completed under the direction of Anthony Sargeant in the Vrije University of Amsterdam. Sadly Jose died some years later while working in Madison, Wisconsin.

New method for the accurate characterization of single human skeletal muscle fibres demonstrates a relation between mATPase and MyHC expression in pure and hybrid fibre type

Jose A A Sant’ana PereiraWessels ANijtmans LAnton F MoormanAnthony J Sargeant.

Journal of Muscle Research and Cell Motility

J Muscle Res Cell Motil. 1995 Feb;16(1):21-34

In the present study we have developed a method which, by combining histochemical, immunohistochemical, electrophoretic and immunoblotting analyses on a single fibre, enables a sensitive characterization of human skeletal muscle fibres dissected from freeze-dried biopsy samples.

For histochemical (and immunohistochemical) analysis fibre fragments (500 microns) of individual fibres were mounted in an embedding medium to allow cryostat sections of normalized thickness to be reproducibly obtained. The specificity of the myofibrillar Ca2+ ATPase (mATPase) staining profiles in gelatin-embedded single fibre sections was tested by immunohistochemical reactions with anti-myosin heavy chain (MyHC) monoclonal antibodies specific to human MyHC I, IIA, IIB and IIA + IIB and by gel electrophoresis. The combined methodologies demonstrated the specificity of the mATPase staining patterns which correlated to the expression of distinct MyHC isoforms. In addition the results provide evidence that many fibres co-expressed different MyHC isoforms in variable relative amounts, forming a continuum.  Staining intensities for mATPase, converted into optical density values by image analysis revealed that a relationship between mATPase and MyHC expression holds for hybrid fibres even when displaying one MyHC type with overwhelming dominance. The results also revealed that three MyHC isoforms I, IIA and IIB can be co-expressed on a single muscle fibre. In such a case mATPase alone, with the current protocols, does not allow an accurate characterization of the specific MyHC-based fibre type(s). Although some hybrid fibres may have displayed a non-uniform expression of myosins along their lengths, most fibres from the IIA/B group (type) remained very stable with respect to the relative amounts of the MyHCs expressed. Finally, a second slow MyHC isoform was recognized on immunoblots of a mixed muscle sample.

Human Muscle Fibre Types

In this important series of studies a collaboration between the research group in Amsterdam led by Anthony Sargeant and that in London under the direction of Professor Geoffrey Goldspink used new techniques based on microdissection of fragments of human muscle fibre obtained by needle biopsy.
Characterization of human skeletal muscle fibres according to the myosin heavy chains they express

Steven EnnionJose A A Sant’ana PereiraAnthony J SargeantArchie YoungGeoffrey Goldspink.

Journal of Muscle Research and Cell Motility
J Muscle Res Cell Motil. 1995 Feb;16(1):35-43
Using a method of single muscle fibre analysis, we investigated the presence of RNA transcripts for various isoforms of the myosin heavy chain (MyoHC) gene in histochemically, immunohistochemically and electrophoretically characterized individual muscle fibres (n = 65) from adult human vastus lateralis muscle. A cDNA clone isolated in this study was shown to contain the 3′ end of a previously uncharacterized human MyoHC gene which is expressed specifically in human fast IIA muscle fibres and we conclude that this clone contains part of the human fast IIA MyoHC gene. In all the fibres histochemically, immunohistochemically and electrophoretically characterized as containing the previously classified IIB MyoHC (n = 23), it was shown that the human equivalent to the rat type IIX MyoHC gene is expressed. This observation was taken to suggest that the previously classified IIB muscles fibres in human muscle express a MyoHC isoform equivalent to the rat IIX, not the IIB, and would therefore be more accurately classified as IIX fibres.