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Advances in Social Sciences Research Journal – Vol. 10, No. 5
Publication Date: May 25, 2023
DOI:10.14738/assrj.105.14652.
Sioud, R., Amara, S., Gaied-Chortane, S., and Khalifa, R. (2023). Effects of Shooting with A Reduced Hoop Diameter Rim on
Kinematics of a Basketball Free-Throw. Advances in Social Sciences Research Journal, 10(5). 37-46.
Services for Science and Education – United Kingdom
Effects of Shooting with A Reduced Hoop Diameter Rim on
Kinematics of a Basketball Free-Throw
Sioud, Rim
Research Unit (UR17JS01)"Sport Performance, Health & Society",
Higher Institute of Sport and Physical Education of Ksar-saïd,
University of Manouba, Tunisia, and Higher Institute of Sport and
Physical Education of Ksar Said, University of Manouba, Tunisia
Amara, Sofiene
Research Unit (UR17JS01)"Sport Performance, Health & Society",
Higher Institute of Sport and Physical Education of Ksar-saïd,
University of Manouba, Tunisia, and Higher Institute of Sport and
Physical Education of Ksar Said, University of Manouba, Tunisia
Gaied-Chortane, Sabri
Research Unit (UR17JS01)"Sport Performance, Health & Society",
Higher Institute of Sport and Physical Education of Ksar-saïd,
University of Manouba, Tunisia, and Higher Institute of Sport and
Physical Education of Ksar Said, University of Manouba, Tunisia
Khalifa, Riadh
Research Unit (UR17JS01)"Sport Performance, Health & Society",
Higher Institute of Sport and Physical Education of Ksar-saïd,
University of Manouba, Tunisia, and Higher Institute of Sport and
Physical Education of Ksar Said, University of Manouba, Tunisia
ABSTRACT
The purpose of this study was to determine the effects of a reduced rim diameter
(diameter 0.30 m) upon the kinematics of basketball free-throws. Ten male
basketball players (mean ± s; age 17.1 ± 0.4 years, height 1.85 ± 1.43 m, mass 79.0 ±
5.3 kg) performed 8 direct successful free throws; 4 when using a standard 0.45 m
diameter rim, and 4 with an 0.3 m diameter rim. Ball release parameters and joint
angles at ball release were determined for each participant. The smaller rim was
associated with significant increases (p < 0.0001) in ball release angle, ball release
velocity, ball release height and shoulder joint angle at release. The reduced
diameter rim can be advocated as a tactic for developing a higher ball release angle
when training the shooting technique of young basketball players; this is likely to
maximize the probability of a successful free-throw when attempted into a standard
rim.
Keywords: Angle of release, height of release, joint angle, velocity of release.
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Advances in Social Sciences Research Journal (ASSRJ) Vol. 10, Issue 5, May-2023
Services for Science and Education – United Kingdom
INTRODUCTION
Shooting is the most frequent technical action in basketball, and is the principal source of points
in games [1]. Accurate shooting is thus a key factor in high performance [2]. A free-throw is
awarded after a single foul penalty (International Basketball Federation, 2010). In this type of
shot, the shooter must throw an official-sized ball (mass 0.56 kg to 0.65 kg; diameter = 0.24 m)
from the free-throw line (4.6 meters from the backboard), through a horizontal 0.45 m hoop
3.05 m above the ground [3]. The free-throw should be one of the easiest shots in basketball
[4], since it is performed without opposition.
Many basketball teams lose games by one to five points, with victory within reach if players had
achieved success with six or seven of ten or more missed free-throws. Several authors [5-8],
underlined that successful free-throws could be the deciding factor in winning or losing
basketball games. Hays and Krause [9] and Mersky. [10] noted that free-throws accounted for
20 to 25% of all points scored. Kozar et al [11] further pointed that opportunities to shoot free- throws increase near the end of close games and converting these opportunities into points is
crucial for success.
The likelihood of a successful free-throw depends on the skill of the shooter and particularly on
the choice of an optimal trajectory [12], defined as one that increases the probability of a
successful shot [13]. Characteristics of a free-throw include the angle, velocity and height of ball
release [1,3]. A highly skilled shooter consistently reproduces the optimal angle-velocity-height
combination [13-15]. The swish aperture decreases with entry angle [13]; a greater angle offers
a wider aperture and a greater possibility of success [1,14,16]. Generally, players attempt a
trajectory where the ball touches neither the hoop nor the backboard [4].
Previous suggestions of optimal release angle-release height combinations for successful free
throws are summarized in Table 1; the most effective angles and heights seem in the range of
49.2° to 60° and 1.52 m to 2.44 m respectively.
Table 1. Predictions for release angle-release height combinations for successful free
throws.
Release angle (°) Release height (m)
Mortimer (1951) 58 1.52
Brancazio (1981) 49.2 2.44
Hay (1994) 52 - 55 2.13
Hamilton and Reinschmidt (1997) 60 2.05
Gablonsky and Lang (2005) 52.0 – 56.6 1.52 – 2.21
Tran and Silverberg (2008) 52 2.13
Free-throw ability is a critical skill for basketball players [13,17], and trainers often require
players to spend many hours practicing shooting drills [7,18]. Gablonsky and Lang [14]
suggested using an insert to narrow the ring and thus allow such practice to develop shots that
passed through the centre of the hoop. Rendell, Farrow et al [19] advocated an adapted ring
with an additional 0.3 m diameter metal barrier. Others [20-22], also, have developed various
devices to narrow the standard rim. However, their effects upon the kinematics of shooting
have yet to be analyzed.
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Sioud, R., Amara, S., Gaied-Chortane, S., and Khalifa, R. (2023). Effects of Shooting with A Reduced Hoop Diameter Rim on Kinematics of a Basketball
Free-Throw. Advances in Social Sciences Research Journal, 10(5). 37-46.
URL: http://dx.doi.org/10.14738/assrj.105.14652
The aim of the current study was thus to assess the effects of using a 0.3 m diameter rim upon
the kinematics of basketball free-throws. We hypothesized that the reduction of rim diameter
would modify ball release parameters and increase the minimum angle of ball entry.
METHODS
Participants
Ten male basketball players (mean ± s; age 17.1 ± 0.4 years, height 1.85 ± 1.43 m, mass 79.0 ±
5.3 kg), volunteered to participate in the study. All of the proposed procedures had been
approved by the Institutional Review Committee for the ethical use of human participants, in
accordance with current national and international laws and regulations. Subjects gave their
written informed consent after receiving both a verbal and a written explanation of the
experimental design and its potential risks. They were informed that they could withdraw from
the study at any time without prejudice to their sport involvement.
All participants had competed in the national basketball players’ youth championship for at
least 6 years; they were right-handed, free of injuries, and fell within the height range of 1.84
to 1.88 m.
Experimental Procedures
Standing height was measured using a wall stadiometer (Tanita, Ancona, Italy) and body mass
was measured to the nearest 0.1 kg using an electronic scale (Seca, Hamburg, Germany). Other
observations on a regulation indoor basketball court before pre-season training. The
parameters examined were the angle, velocity, height at ball release and the corresponding
angles at elbow, shoulder, trunk, knee and ankle joints. As with Miller and Bartlett [3] and Uygur
et al [17], wrist angles were not examined.
In the first evaluative session, participants performed 15 minutes of warm-up exercises [8], and
then practiced free-throw shooting for 5 minutes, using a standard [23]. Retro-reflective
spherical markers of 5 mm diameter were attached by adhesive tape unilaterally on the right
side of the body at the second distal phalangeal joint (right hand finger), styloid process of ulna
(wrist) the lateral epicondyle of the humerus (elbow joint), the acromion process (shoulder)
[24], pelvis (anterior superior iliac spine), the lateral epicondyle (knee), distal end of fibula
(lateral malleolus), the heel of the shoe (calcaneous; at the same height above the plantar
surface of the foot as the phalange marker) and at the 5th metatarsophalangeal joint [17]. Five
10 mm diameter markers were attached to the ball at the left and right medial–lateral axes, and
at approximately 0.05 m from the right axis marker in three directions, thus forming a triangle
[23]. Each participant performed free-throws using a standard rim until four successful shots
had been accomplished where the ball did not touch either the hoop or the backboard [1,3,24].
Twenty-four hours later, a second evaluation was made, shooting into a 0.3 m diameter rim.
Participants again performed a 15-min warm-up with standardised exercises [8] and then
practiced free-throw shots until they were ready for data capture [23].
Determination of Minimum Entry Angle
We used the equation proposed by Hay [1]:
rim
ball
d
d
sin =