Biomechanics and Medicine in Swimming XI

BiomechanicsandmedicineinswimmingXi
about 10%), underlining the importance of simultaneously considering
both energy cost and its biomechanical determinant factors. Holmér
elaborated on the swimming economy of the four competitive strokes,
relating it to P, D, IVV and buoyancy.
Training contributions were scarce (Miyashita and Kanehisa), or
partially hidden by their common physiological (Cazorla et al.; Nomura;
Treffene), biomechanical (Schleihauf ) or EMG (Olbrecht and Clarys)
content. However, physiology and thermoregulation presented relevant
and innovative contributions (Chatard et al.; Craig; Nielsen; Novák et
al.; Zeman et al.). Decisive, also for its rarity as a longitudinal design,
and for the preservation of the Swedish tradition in this regard, was
the five year follow-up physiological study of Gullstrand and Holmér.
Lavoie et al. presented the backward extrapolation method for the assessment
of VO 2 in swimming reducing the mechanical constrains imposed
by masks and tubes.
BMS V (1988)
One of the main topics was, once more, the P production mechanism.
Although De Groot and Van Ingen Schenau theoretically demonstrate
why L dominated propulsion is more efficient than Dp dominated P
forces, Ungerechts showed that peak acceleration of the breaststroker
during the kick happens near the turning phase of the feet, suggesting
that a quasi-static approach to the hydrodynamics of P in swimming
seems to be insufficient. In parallel, Shleihauf et al. went even deeper in
the quasi-static propulsive theory, and provided evidence of four propulsive
phases in backstroke arm action. Concerning D, the “MAD-
System” was referred to in the series for the first time. A very creative use
of the device allowed Hollander et al. to show that the leg contribution
to total power output in front crawl is only slightly higher than 10%.
Toussaint et al. used the same system to show that propelling efficiency
decreases with swimming v (r = -0.84) between 1.05 and 1.3 m/s. The
EMG validations of the “MAD-System” (Clarys et al.) and tethered
swimming front crawl (Bollens et al.) were also provided. Consequently,
the relationships between stroke frequency, tethered force and EMG,
found by Cabri et al., gained increased relevance for front crawl performance
analysis.
Using inverse dynamics from the IVV curve, Van Tilborgh et al. calculated
the resultant impulses per phase of the breaststroke technique,
emphasizing the importance of body undulation in this technique. This
was one of the few studies of this volume centered on IVV assessment.
However, this parameter was the basis of a historical paper on swimming
evaluation and advice (Persyn et al.), integrated with force and
flexibility measurements, hydrodynamics, hydrostatics and other biomechanical
data, as well as with markers of aerobic and anaerobic capacities,
anthropometry, and performance parameters.
Medical contributions were mainly restricted to the analysis of
chronic injuries related to swimming sports (Mutoh et al.), while physiological
contributions were vast and mostly referred to evaluation (Olbrecht
et al.), training (Van Handel et al.; Yamamoto), and performance
(Chatard et al.; Telford et al.), mostly considering [La-] responses, and
in some cases combined with VO 2 and stroking parameters (Keskinen
and Komi). The training content was explicitly related to physiology,
mainly because the latter essentially referred to energy metabolism and
to swimming economy, and associated factors (Cazorla et al.; Montepetit
et al.; Van Handel et al.).
BMS VI (1992)
The theoretical increase of SL with efficiency and power output, and
decrease of drag and stroke frequency (Toussaint), allows retaining this
parameter as a measure of swimming proficiency. This is, perhaps, one
of the reasons why several papers were devoted to stroke parameters
and competition analysis (Keskinen and Komi; McArdle and Reilly;
Wakayoshi et al.; Wirtz et al.). Propelling and mechanical efficiencies
were also specifically addressed (Cappaert et al. a, b), although a swimming
economy profile was criticized as a swimming skill measurement
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(Chatard et al.). One of the factors already theoretically associated with
efficiency is the IVV, a topic that regains its traditional importance in
this volume (Chollet et al.; Hahn and Krug; Manley and Atha; Mason
et al.; Persyn et al.; Tourny et al.; Ungerechts). Ungerechts, Persyn et
al. and Mason et al. used videogrametry, but both Manley and Atha,
and Hahn and Krug used the swim-speed-recorder technology, based
on an impeller attached to the swimmer’s body to monitor swimming
velocity, and Chollet et al. used a more conventional cable speedometer.
Two most relevant conclusions emerged from these studies: (i) most of
the breaststroke studies revealed a two peak IVV profile, and (ii) IVV
tends to reduce with mean velocity, including the number of velocity
peaks per stroke.
EMG was also a very relevant topic in this volume covering issues
like effects of front crawl speed (Rouard et al.), paddle swimming (Monteille
and Rouard), swimming fins (Cabri et al.), water polo (Clarys et
al.) and Synchronized swimming (Zinzen et al.).
Physiological contributions were many; they were focused on pure
swimming but also on water polo (Hohmann and Frase) and life saving
(Daniel and Klauck). Particular emphasis was given to lactate metabolism
and testing (Kelly et al.; Keskinen and Komi; Olbrecht et al.; Peyreburn
and Hardy; Roi and Cerizza). However, it should be underlined
that also much attention was dedicated to the study of the aerobic and
anaerobic contributions to different training sets and performances, and
its variation with work / rest ratios (Troup et al.), age and performance
level (Takahashi et al.).
Of particular interest was the attempt to match anthropometrical
and technical profiles (Colman et al.) relating physical characteristics
and undulation in breaststroke, as well as to establish a psychological
profile that predisposes for swimming performance (Stallman et al.),
considering self-control and motivation, both for training and competition.
BMS VII (1996)
Energy related biomechanical factors were at the centre of this BMS
volume. Sanders (a, b) provided evidence supporting the idea that body
undulation may contribute to increased propulsion and/or reduced drag,
while Vilas-Boas and Alves et al. provided evidence of the relationship
between energy cost and IVV in swimming, respectively for breaststroke
and backstroke. Moreover, Vilas-Boas found that flat breaststroke was
more economical than undulating variations, contradicting the tendency,
at the time, to emphasize body undulation. Convergently, Cappaert
et al. stated that top breaststrokers are characterized by lower IVV
than their lower performance counterparts, and emphasized that higher
level Olympic butterfly swimmers show lower trunk angulation to the
horizontal. Cappaert, however, wasn’t able to find any correlation of
the segmental and full body angular momentum around the CM with
swimming performance in a sample of 8 breaststrokers. Energy was also
the focus of other contributions, namely considering sprint swimming
metabolism (Ring et al.), aerobic/anaerobic energy partition during a
400m freestyle event (Nomura et al.) and energy expenditure during
heavy training and taper (Trappe et al., Van Heest).
Wakayoshi et al. provided another contribution explicitly relating
physiologic and biomechanical parameters during swimming. They
found an interesting coincidence between the OBLA intensity and a
“biomechanical turning point”, where SL decreases and SR increases are
observed during an incremental front crawl test (SL drop).
Swimming propulsion continued to be addressed. Berger et al.
compared propulsive forces measured through the MAD-System and
a Shleihauf-like quasi-static approach. The MAD-System underestimated
the quasi-static effective propulsive force by about 15%. Rouard
et al. studied the time duration and the impulse of the different P force
components in each phase of the freestyle arm-stroke cycle, concluding
the non-existence of significant correlation between these variables and
performance. The authors also found higher propulsive drag than lift
impulses throughout the stroke.