SPINE Volume 30, Number 20, pp 2350–2355©2005, Lippincott Williams & Wilkins, Inc.

Giovanni Alfonso Borelli—The Father of Biomechanics

Malcolm H. Pope, DrMedSc, PhD

Giovanni Alfonso Borelli is often described as the fa-ther of biomechanics. He was born in Naples in 1608. HisDe Motu Animalium, published in 1680, extended to biol-ogy the rigorous analytical methods developed by Galileoin the field of mechanics. Borelli calculated the forcesrequired for equilibrium in various joints of the humanbody well before Newton published The Laws of Motion.Borelli was the first to understand that the levers of themusculoskeletal system magnify motion rather thanforce, so that muscles must produce much larger forcesthan those resisting the motion. Borelli died in Rome onDecember 31, 1679, but his impressive body of originalwork helped inspire a great number of future scientists,microscopists, and inventors. The highest honor be-stowed by the American Society of Biomechanics is theGiovanni Borelli Award. Spine 2005;30:2350–2355

Giovanni Alfonso Borelli is often described as the fatherof biomechanics (Figure 1). He was born in Naples, Jan-uary 28, 1608. Borelli deliberately obscured his date andplace of birth to conceal his connection to his father’spolitical difficulties, and his own connections withGiovani Domenico Campanella, who was a political pa-riah. (Giovani Domenico Campanella was born in Stilo,Calabria in 1568. He entered the Dominican order andtook the name Tommaso, where he received training inphilosophy and theology. His questioned Dominican or-thodoxy and was denounced to the Inquisition. He wasimprisoned for 27 years for trying to expel the Spanishfrom Naples and Sicily. During these imprisonments, hewas tortured several times.2) Borelli was the firstborn sonof a Spanish infantryman, Miguel Alonso, and a localItalian woman of Naples, Laura Porello.3 His originalname was Giovanni Francesco Antonio Alonso. He diedin Rome on December 31, 1679. It is possible that Tom-maso Campanella taught him while Campanella was aprisoner at the Castel Nuovo, Naples, where Borelli’sfather was stationed. He may have received medicaltraining at the University of Naples. After 1628, he be-came a student of Castelli in Rome.

Borelli contributed both to the mathematical andphysical sciences (mainly astronomy and mechanics),

and the medical and the biologic sciences. His De MotuAnimalium, published in Rome in 1680, was an attemptto extend to biology the rigorous analytical and geomet-rical method developed by Galileo in the field of mechan-ics.4 He became a student of Galileo’s former student,Benedetto Castelli, founder of the science of hydraulicsin Rome. (Antonio Castelli [1577/8–1643] was born inBrescia, Italy. He took the name Benedetto on enteringthe Benedictine order in 1595. On Galileo’s recommen-dation, Castelli was appointed professor of mathematicsat the University of Pisa in 1613.)

Academic Career

It was Castelli who recommended Borelli to the Univer-sity of Messina for the vacant chair of mathematics.Borelli studied physics in Galileo’s class at Pisa. Borellitaught mathematics at the University of Pisa and later atthe University of Messina. He was a member of the Ac-cademia del Cimento (Academy of Experiments).Founded in 1657 in Florence by the Medici brothers,Prince Leopold and the Grand Duke Ferdinand II; theAccademia lasted only until 1667. However, its publica-tion Saggi di Naturali Esperienze Fatte nell Accademiadel Cimento was very influential. He took part in nearlyall the experiments performed by the Accademia despitefrequent clashes with Carlo Renaldini (1615–1679),whom he called the “Simplicius” of the Cimento. TheAccademia marked the beginning of modern physics.

Borelli was primarily a mathematician during the firsttwo decades of his career. In 1658, he published EculidusRestitutus. In 1637, he was awarded a Public Lecture-ship in Mathematics at Messina. In 1642, the Senate ofMessina made him a member of the city nobility, pro-vided him with considerable funding, and sent him on atour to hire teachers away from leading Italian universi-ties. Between 1656 and 1667, at the behest of the PrinceLeopold de’ Medici, he became professor of mathematicsat Pisa. Between 1667 and 1672, he returned to Messinaand resumed his chair. After the anti-Spanish rebellion inMessina in 1670, Borelli was forced to leave Sicilyin 1670. He moved first to Calabria and then to Rome. InRome, he petitioned Cassini, a member of the Academie,for royal support, and he became a member of the Acad-emy founded by Queen Christina of Sweden. He alsobecame the physician of Queen Christian. The ClerksRegular of the Pious Schools (Piarists or Scolopians) alsosupported him in 1677. Between 1677 and 1679, hetaught mathematics at the Scuole Pie, to novices of theOrder in Rome. Negotiations were underway for dedi-cation of De Motu Animalium, in 1677, when all ofBorelli’s belongings were stolen. In 1679, he eventually

From the Liberty Safework Centre, University of Aberdeen, Aberdeen,United Kingdom.Acknowledgment date: September 10, 2004. Acceptance date: January11, 2005.The manuscript submitted does not contain information about medicaldevice(s)/drug(s).No funds were received in support of this work. No benefits in anyform have been or will be received from a commercial party relateddirectly or indirectly to the subject of this manuscript.Address correspondence and reprint requests to Malcolm H. Pope,DrMedSc, PhD, Liberty Safework Centre, University of Aberdeen, For-esterhill Road, Aberdeen, AB25 2ZB, United Kingdom; E-mail:m.pope@biomed.abdn.ac.uk

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dedicated De Motu Animalium to Queen Christina, whohad agreed to pay the printing costs.

Contributions to Diverse Fields

He was a prolific contributor to very diverse fields. Hewas an important figure in the development of the cor-puscular or mechanical philosophy, hydraulics, and me-teorology. From 1647 to 1648, the senate of Messinaappointed him to study the epidemic fevers ragingthrough the population. He devised a treatment, al-though it does not seem to have been widely applied.Subsequently, he published a pamphlet entitled DelleCagioni de le Febbri Maligna (On the Causes of Malig-nant Fevers) (Rome, 1649). He also performed an impor-tant investigation of volcanoes. In Pisa, Borelli per-formed extensive anatomic dissections. In 1665, heestablished an observatory at the fortress of San Miniatowith some instruments of his own design. While in Flo-rence, he edited books on hydraulics and worked for theGrand Duke on lagoons near Pisa. Borelli proposed amethod of determining longitudes with a clock.

Borelli worked on a compendium of Apollonius’s 4surviving books, which was published in Rome in 1679.

He conducted a revision of Euclid’s Elements (publishedin 1658 as Euclides Restitus). At the University of Pisa,Borelli was heavily involved in the scientific programsorganized by Prince Leopold de’ Medici (1617–1675).Borelli’s chief contribution during his stay in Tuscanywas his research in astronomy and on Jupiter’s moons,described in the Theoricae Mediceorum Planetarum exCausis Physicis Deductae (Florence, 1666). Borelli pro-posed the curvilinear motion of planets driven by 2forces: a centrifugal force and an attraction to the sun.Galileo had never accepted Kepler’s elliptical orbits, de-riving circular ones instead. In a letter published in 1665under the pseudonym Pier Maria Mutoli, Borelli was thefirst to suggest that comets travel in a parabolic path. Healso predicted the orbits of Jupiter’s moons by consider-ing the influence of both Jupiter and the sun.

Extremely inventive, Borelli is recognized by scubadiving enthusiasts for his drawings of a closed circuit“rebreather.” His illustrations depict a giant bag usingchemical components, which he suggested should allowthe air to be breathed again by a submerged diver. In1667, Borelli left the Medici family and returned toMessina. During the same year, he published De vi Per-cussionis in Bologna, a compilation and expansion of hisresearch in physics undertaken at the Accademia del Ci-mento. He is most known for De Motu Animalium (On

Figure 1. The painter Cavalier Ghezzi made this posthumous por-trait of Borelli from an original sketch by Ciro Ferri. Ferri’s sketchhas not been discovered.1

Figure 2. The physician and microscopist Marcello Malpighi, pro-fessor of theoretical medicine at the University of Pisa.

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Animal Motion) but also is recognized for his micro-scopic investigations of red blood cells and his accurateobservation of the regularity of stomatal movements inplants.

Biomechanics

His masterpiece was De Motu Animalium (On AnimalMotion) (Rome, 1680–1681). It was published posthu-mously in 2 parts between 1680 and 1681.5 The book isin 2 parts. The first part examines the external motions ofthe musculoskeletal system in animals from a mechanicalviewpoint. The second part examines internal motions,such as the physiology of muscles and circulation. It is abook of mechanical analogies, a notable early exampleof the use of illustrations to understand natural phenom-ena. It had become evident to Borelli that the science ofmechanics needs to be applied to the study of human andanimal motion to understand the motor control of bio-logic systems. He was the first to explain muscular move-ment and other body functions according to the laws ofstatics and dynamics.

At Pisa, a colleague, the physician and microscopistMarcello Malpighi (Figure 2) (Professor of theoretical

medicine at the University of Pisa), introduced him to thestudy of anatomy. Apparently, the 2 men had a closerelationship, as Malpighi recalls:5 “What progress I havemade in philosophising stems from Borelli. On the otherhand, dissecting living animals at his home and observ-ing their parts, I worked hard to satisfy his keen curios-ity.” It is unclear whether Borelli was a trained physician,and, perhaps, he needed to work with Malpighi to ensurethat his mechanical calculations made biologic sense. Al-though Borelli’s knowledge of mechanics was restrictedto the principle of levers and triangle of forces, he wasable to generate an accurate and comprehensive accountof muscle action.3 The 2 conducted numerous anatomicdissections. Malpighi became the greatest of the earlymicroscopists and the father of embryology. He, Borelli,and Descartes were key figures in establishing the iatro-physical approach to medicine, which held that mechan-ics rather than chemistry was the key to understandingthe functioning of the human body. After a disagreementbetween Malpighi and Borelli, Borelli left Pisa and re-turned to Messina.

In his work De Motu Animalium, Borelli was the firstto understand that the levers of the musculoskeletal sys-

Figure 3. Plate showing Borelli’sanalysis of different speciescompared to man.

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tem magnify motion rather than force, so that musclesmust produce much larger forces than those resisting themotion (Figure 3). This was contrary to the thinking ofthe time (Figures 4 and 5). With an understanding ofstatic equilibrium, Borelli calculated the forces requiredfor equilibrium in various joints of the human body wellbefore Newton published The Laws of Motion.

He also determined the position of the human centerof gravity, calculated and measured inspired and died airvolumes, and showed that inspiration is muscle drivenand expiration is a result of tissue elasticity. His workincluded muscle analysis and a mathematical illustrationof movements, such as running and jumping. Borelli alsoattempted to clarify the reason for muscle fatigue, ex-plain organ secretion, and hypothesize on the concept ofpain.

One of the revolutionary mechanical features of thebody noted by Borelli was that the muscles act with shortlever arms so that the intervening joint transmits a forcethat is a magnitude higher than the weight of the load.Borelli overturned older concepts of muscle action,which stated that long lever arms allowed weak musclesto move heavy objects.2 Borelli noted that “Galen also

states that a tendon is like a lever. He thinks that, conse-quently, a small force of the animal faculty can pull andmove heavy weights. This general opinion seems to be solikely that, to my knowledge, nor surprisingly, it hasbeen questioned by nobody. Who indeed would be stu-pid enough to look for a machine to move a very lightweight with a great force, i.e., use a machine or contriv-ance not to save forces but rather to spend forces? Thisseems strange and against common sense, I agree, but I

Figure 4. Plate showing Borelli’sanalysis of different joints in man.1, Conjunction of 2 levers (longbones), IFS and HDR, at pivotpoint C. 2, How elastic bands(muscles) attached externally tothe levers (at D and F) and to thepivot (B) might bring the leverscloser to each other. 3, The elas-tic bands attached externally tothe levers so that they can be“expanded.” 4, A twin-lever sys-tem, in which the levers are ofunequal length. 5 and 6, Themuscle and bone configurationsin 2 human beings carrying dif-ferent loads. 7 and 8, Studies ofpulley arrangements. 9 and 10,Actions of muscles that enable ahuman being to hold a weightwith an extended arm.

Figure 5. Comparison between the lever arm concept ofArchimedes and Borelli. A, Archimedes showed that the lever armfor force was bigger than the arm used for resistance. It took littleforce to move a large resistance. B, Borelli showed the spine ashe set it up, used a lever arm shorter than the resistance arm, andthe body actually used more force than the force because of theweight of the object lifted or moved.

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can convincingly demonstrate that this is what happensand, given permission, that the upholders of the oppositeopinion have been mistaken.”

Spine Biomechanics

Borelli showed an incredible understanding of spine bi-omechanics. He proposed that the discs must performsome load sharing because his calculations revealed aninability of the spinal musculature alone to supportheavy weights. He proposed that the intervertebral discswere viscoelastic, and both cushioned the bones andacted like springs. He made detailed calculations describ-ing the forces on individual vertebrae when a load wascarried on the neck (Figure 6).2 “If the spine of a steve-dore is bent and supports a load of 120 lb carried on theneck, the force exerted by Nature in the intervertebraldiscs and in the extensor muscles of the spine is equal to25,585 lb. The force exerted by the muscles alone is notless than 6404 lb. Therefore, the sum of the muscularforces GH which control the fifth lumbar vertebra and athird of the resistance of the intervertebral disc is equal to826 lb. The muscular forces are equal to 413 lb and theforces exerted by the disc are equal to 1239 lb.” Thesefigures, produced by Borelli over 300 years ago, agreequite well with modern experimental calculations of spi-nal load sharing. One of the greatest mechanical featuresnoted of the body, as was shown by his analysis, was thatthe muscles act with short lever arms so the joint trans-mits a force that is a magnitude higher than the weight of

the load. Borelli overturned older concepts of muscleaction, which were that long lever arms allowed weakmuscles to move heavy objects.

Equilibrium of RotationBorelli wrote, “Galen also states that a tendon (muscleworking on joint) is like a lever. He thinks that, conse-quently, a small force of the animal faculty (muscle ef-fort) can pull and move heavy weights. This generalopinion and surprisingly, to my knowledge, has beenquestioned by nobody. Who indeed would be stupidenough to look for a machine to move a very light weightwith a great force i.e., use a machine or contrivance notto save forces but rather to spend forces? This seemsstrange and against commons sense, I agree, but I canconvincingly demonstrate that this is what happens andgiven, permission, that the upholders of the oppositeopinion have been mistaken.”

Borelli’s AnalysisBorelli showed a stevedore with a weight carried at theneck that each vertebral joint (individual lever system) inthe lower back used an effective effort arm (created by theposition of the muscle relative to the disc or fulcrum) thatwas shorter than the effective resistance arm (created bythe position of the weight relative to the disc or fulcrum).This lever system requires more effort than the weight ofresistance, which ran against common thought. Why usean ineffective lever system, was essentially the thoughtthat Borelli leaves us with.

Figure 6. A and B, Borelli’s anal-ysis of a stevedore with a weightcarried at the neck.

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The Legacy

Borelli is frequently given the title “father of biomechan-ics.” Most notably, he was one of the founders of “iat-romechanics,” or the application of mechanics to physi-ology. This field is the forerunner of what we now callbiomechanics.

Borelli died in Rome on December 31, 1679, but hisimpressive body of original work helped inspire a greatnumber of future scientists, microscopists, and inven-tors. The highest honor bestowed by the American Soci-ety of Biomechanics is the Giovanni Borelli Award,which is given annually to an investigator who has con-ducted exemplary research in biomechanics.

Summary

Giovanni Alfonso Borelli is described as the father ofbiomechanics. He had a distinguished academic career.He held the chair of mathematics at the University ofMessina. He later became professor of mathematics atPisa before returning to Messina. He was a prolific Hismagnum opus was De Motu Animalium (On Animal

Motion) (Rome, 1680–1681). It was published posthu-mously in 2 parts between 1680 and 1681. In De MotuAnimalium, Borelli was the first to understand that thelevers of the musculoskeletal system magnify motionrather than force, so that muscles must produce muchlarger forces than those resisting the motion. The highesthonor of the American Society of Biomechanics is theGiovanni Borelli Award, which is given annually to aninvestigator who has conducted exemplary research inbiomechanics.

References

1. Middleton WEK. A little-known portrait of Giovanni Alfonso Borelli. MedHist 1974;18:94–5.

2. Schmitt CB. Campanella, Tommaso. In: Dictionary of Scientific Biography.Vol. 15. 68–70.

3. Borelli GA. On the Movement of Animals. Berlin, NY: Springer-Verlag; 1989.[Maquet is the translator.]

4. Blackwell RJ. A Defence of Galileo, the Mathematician from Florence byThomas Campanella. Notre Dame, IN: University of Notre Dame Press; 1994.[Blackwell is the translator.]

5. Adelmann HB. Marcello Malpighi and the Evolution of Embryology. Ithaca,NY: Cornell Press; 1966.

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