1. Introduction
Traumatic brain injuries constitute a significant economic and social burden. It is estimated that sixty-nine million people worldwide suffer from traumatic brain injury (TBI) [
1], of which approximately 75% are mild traumatic brain injuries (mTBI) [
2]. Seemingly minor brain injuries disrupt brain function. Literature reports indicate that, in the long term, the most dangerous are repetitive minor head injuries. These sorts of injuries can cause changes in neurotransmitter systems, which play a crucial role in maintaining homeostasis in behavioral and cognitive functions. Specific brain regions, such as the frontal cortex, white matter of the prefrontal region, rostral brainstem, and temporal lobes with the hippocampus, are particularly susceptible to damage [
3]. The studied research shows that frequent brain injuries lead to the accumulation of tau protein in the brain, which is strongly associated with dementia syndromes [
4]. Consequently, head injuries are a compelling risk factor for the development of neurodegenerative diseases, including Alzheimer’s disease [
5,
6], Parkinson’s disease, and chronic traumatic encephalopathy [
7].
Considering psychological aspects, it should be noted that mechanical injuries can cause numerous cognitive dysfunctions. The disorders may appear immediately after injury or be chronic. Frontal lobe damage, responsible for executive functions such as problem-solving, attention shifting, impulse control, and self-monitoring, is common [
8,
9]. Other frequently affected functions include concentration [
10,
11], short-term memory, learning [
9,
12,
13,
14], information processing speed [
15], and speech and language functions [
16,
17,
18,
19,
20]. Research indicates that individuals with traumatic brain injuries often experience emotional control disorders and personality changes, manifesting as impulsivity, irritability, affective instability, and apathy due to motivational behavior deficits [
21]. Moreover, literature descriptions suggest that brain injuries increase the relative risk of psychiatric disorders, such as mood disorders, anxiety, substance abuse, and psychotic syndromes [
22,
23,
24].
According to data available from the Centers for Disease Control and Prevention (2023), approximately 3.8 million brain injuries occur annually in the United States, 10% of which result from sports and recreational activities. Among American children and adolescents, these activities account for over 21% of all brain injuries [
25,
26]. However, it is essential to highlight that the estimated incidence of this phenomenon is based solely on hospitalized patients and does not account for injured individuals who do not seek medical assistance or lack access to healthcare services.
One of the primary causes of brain structure damage is mechanical overload [
27,
28]. The high risk of developing long-term neurological dysfunctions due to frequent micro-injuries to brain tissue is most common among athletes practicing contact sports [
29,
30]. High-risk sports include combat sports such as boxing [
31]. This issue was first highlighted in 1928 by Harrison Martland [
32], who described a case of a boxer suffering from cognitive disorders due to repeated head blows and episodes of concussions sustained in fights. Another example is Muhammad Ali, who was diagnosed with speech and movement retardation [
33]. According to the Boxing-Related Head Injuries data, between 1732 and November 2007, 1465 boxers died from traumatic brain injuries [
34].
Despite the high risk of brain injury, boxing has several benefits for the nervous system. During fights, quick thinking, decision-making, and strategy are crucial, helping to develop cognitive skills such as concentration, visual–motor coordination, and psychomotor reactions. Due to its high-intensity training, boxing can improve blood flow to the brain, supporting cognitive function [
30,
35]. Additionally, it enhances overall fitness and offers various health benefits, including stress reduction [
36]. Consequently, boxing has become increasingly popular, attracting more amateur participants each year. Statistical data published by the Statista Research Department, based on an analysis conducted in the USA between 2018 and 2023, indicate that approximately 8.4 million people over the age of six practice boxing, with about 3.4 million participating in boxing as a recreational activity [
37].
The safety of contact sports athletes is primarily influenced by sports equipment [
38,
39,
40,
41]. Therefore, the development of protective elements and systems is crucial. Since 1904, boxing gloves have been the primary protective equipment used in amateur and Olympic boxing to absorb and disperse part of the impact energy exchanged between boxers. Theoretically, boxing gloves significantly reduce punch intensity, protecting the athletes’ hands [
42,
43]. However, in boxing, the athletes’ brains undergo rapid accelerations, causing the brain to collide with the skull [
36,
44,
45]. Repeated occurrences of this mechanism over the long term result in numerous neurological consequences [
46,
47].
Despite the ubiquitous use of boxing gloves and headgear in both training and competition, their actual biomechanical effectiveness in attenuating head loading remains insufficiently quantified. In particular, there is a lack of experimental data examining how gloves and headgear interact and how their protective performance depends on striker-specific biomechanics, such as punch execution characteristics and individual force-generation capacity. This knowledge gap is especially relevant given the wide variability in equipment design, material properties, and user behavior, which may substantially influence head kinematics and injury risk.
The current literature contains few studies on boxing gloves and their ability to absorb impact energy. Most research was conducted three decades ago [
48,
49,
50]. At that time, glove padding consisted of a layer of horsehair sandwiched between two layers of low-density foam, covered with natural leather [
48]. Given this, available studies provide limited information on energy absorption capacity since glove manufacturing processes and materials have evolved significantly over the years. Selecting appropriate glove materials is crucial for protecting athletes’ health. Walilko et al. demonstrated that adequate boxing glove padding significantly reduces peak impact force values [
50].
A boxing helmet is an essential piece of protective equipment for combat sports athletes, designed to reduce the risk of head injuries during training and competition. Their primary function is to absorb the kinetic energy of impact and protect the cranial and cerebral structures from direct contact with an opponent. Various types of helmets are used in sports, from training models that cover the entire face to amateur helmets used in competitions that leave part of the face exposed [
39]. Despite their widespread use, scientific evidence indicates that protective headgear provides only partial protection and does not fully prevent concussive injury. Some studies confirm that helmets reduce the risk of superficial injuries, such as cuts and bruises [
51], but their impact on concussion prevention remains inconclusive [
52]. Some studies even indicate that helmets may increase the risk of brain injury due to changes in distance perception and increased head moment of inertia [
53].
The effectiveness of a helmet’s impact is broadly determined by its structure, layering, and the properties of the impact-absorbing materials [
54]. A typical boxing helmet consists of several layers: a synthetic plastic layer (e.g., polyurethane or synthetic leather), a closed-cell foam (most often EVA—ethylene vinyl acetate or PU—polyurethane foam), and a layer to prevent perspiration. Biomechanical studies have shown that elastic-damping effects are side effects resulting from the use of simultaneously accelerated linear and rotational heads, which pose a major risk to the brain [
50,
55]. In recent years, new materials have also been developed, such as variable frequency power supplies, thermoplastic elastomers (TPEs), and shape memory composite structures that better adapt to different impact powers [
56].
According to Hoshizaki et al., so-called multi-impact helmet liners that absorb impact energy—such as vinyl nitrile (VN) or expanded polypropylene (EPP)—dissipate the impact energy by undergoing elastic deformation and then returning to their original shape [
57]. However, EPP is more resistant to higher-energy impacts than VN, but it degrades faster than VN under such loading [
57]. The energy-absorption capacity of these helmets is influenced by the foam’s thickness and density [
57]. The higher the foam material’s density, the greater its ability to withstand high-energy impacts. In addition, when dissipating the impact energy absorbed by the helmet, not only does the material type matter, but also its stiffness and geometry [
58,
59].
The average impact forces of novice boxers are on the order of several kilonewtons [
60]. Impacts of this magnitude significantly exceed or are comparable to the biomechanical tolerance of various facial bone regions, such as the nasal bone (0.5 kN), the maxilla (0.7–1.5 kN), the mandible (1.4 kN), the lateral part of the skull (2.0–3.6 kN), or the temporo-parietal region (2.5–5.2 kN) [
61]. Boxing punches involve a transfer of kinetic energy and a change in momentum, governed by the relationship between impact force (F), duration (Δt), and the target mass (m). The energy transferred during the impact is partially dissipated within the helmet and partially contributes to its deformation (Δx). For novice boxers, striking at velocities of approximately 5 m/s [
61], punch power (P) can exceed 11 kW [
60]. The resulting deformation of the protective layers is determined by the portion of the impact energy that is not dissipated through the material’s internal damping mechanisms [
59].
Several scientific articles have been published examining the reduction in acceleration provided by a rugby helmet ([
62,
63,
64,
65], but almost all of them focus exclusively on linear kinematics. These studies demonstrated that the rugby helmet significantly reduced the peak linear acceleration (PLA) observed during laboratory impacts. The helmet meets the attenuation criteria if the PLA is greater than 200 g. In addition, the helmet has strict thickness and density limits: 10 ± 2 mm and 45 kg/m
3, respectively. There are several other conditions that must be met for a helmet to be approved by World Rugby, including the strength and effectiveness of the retention system and obstruction of the field of vision [
66,
67].
This study aims to biomechanically assess available boxing equipment solutions and identify the brain–skull system’s response to physical forces from a boxing punch. This study involved the development of a specialized measurement setup using acceleration sensors and a high-speed camera to record the physical response of human head tissues to a biologically delivered punch. We state the following: the use of head protection reduces peak head acceleration compared with no protection; increased helmet mass may lead to higher selected kinematic responses due to increased moment of inertia; glove mass modifies head acceleration depending on punch biomechanics and performer characteristics.
4. Discussion
The human brain is the most important organ and requires the greatest protection. In contact sports, we can identify several methods to reduce the risk of head injuries, including personal protective equipment such as gloves or helmets. The aim of this study was to biomechanically evaluate available boxing equipment and to determine the response of the cranial–cerebral system to the physical forces generated by a boxing punch. This objective was achieved, and the predefined hypotheses were partially confirmed: head protection reduced peak linear acceleration in several configurations; increased helmet mass was associated with higher kinematic responses in selected cases; and glove mass influenced head loading depending on punch biomechanics. Given the pilot nature of the work (n = 2), these findings should be interpreted as mechanistic observations rather than population-level estimates.
Across conditions, the dummy exhibited a damped oscillatory head tilt response, with the largest angular excursions occurring after ungloved impacts. Increasing glove mass reduced head tilt amplitude, and both helmets attenuated rotational motion, with the boxing helmet showing the greatest damping effect, followed by the rugby headguard. Peak head acceleration values consistently clustered within a range across several glove–headgear combinations, indicating that equipment-related differences at these impact energies are modest. Notably, HIC values remained similar across all test configurations, underscoring the limited sensitivity of the HIC to moderate variations in protective-equipment design and highlighting the importance of including rotational metrics in injury risk assessment.
This study also revealed characteristic differences between the two headgear types. The boxing helmet occasionally generated higher linear accelerations, due to its greater mass and the resulting increase in rotational inertia, whereas the lighter open-cell rugby headguard dissipated low-energy impacts more effectively. No consistent relationship was observed between glove mass and head acceleration across participants, reflecting the influence of individual biomechanics and striking technique.
Beyond these findings, this study provides four methodological contributions: (a) a dual-modality measurement framework combining IMUs with high-speed video, enabling simultaneous analysis of linear and rotational head responses; (b) empirical demonstration of HIC insensitivity in low-to-moderate boxing-like impacts; (c) the first controlled comparison of training boxing headgear and competition-approved rugby headgear under identical conditions; and (d) a repeatable laboratory protocol that balances controlled posture and punch trajectory with human-generated impacts, suitable for future larger-scale studies. Overall, the results illustrate the multifactorial nature of head-impact mitigation and emphasize that evaluating protective equipment requires attention not only to peak linear acceleration but also to rotational dynamics and the interaction between equipment mass, material properties, and user biomechanics.
Biomechanical studies have shown that the elastic-damping properties of the foam are crucial for reducing both linear and rotational head acceleration, which are major risk factors for brain injury [
50]. In recent years, new materials have also been developed, such as variable-density foams, thermoplastic elastomers (TPEs), and shape-memory composite structures, which better adapt to varying levels of impact force. Additionally, the use of numerical simulation technologies (e.g., finite element methods) allows for more precise analysis of force distribution within the head and optimization of helmet designs to minimize brain acceleration [
56]. Advances in polymer materials and safety engineering have enabled power supplies to be activated by adaptive adapters to various impact signals and to be captured by the rotational energy transferred to the control system [
71,
72]. This research has implications not only for boxing but also for the broader context of safety in contact sports.
Our results indicate that the protective effectiveness of these elements is not unambiguous and depends on a range of physical, structural, and psychological factors. The use of a boxing helmet was intended to reduce the loads acting on the head by increasing contact time and dispersing the impact energy. In practice, however, cases were observed in which head acceleration values increased compared to the situation without protection. This effect can be attributed to the increased mass of the head–helmet system, which leads to a higher moment of inertia and the generation of greater rotational accelerations—a key factor in the mechanisms underlying concussion [
73,
74,
75,
76].
The test results also indicate that heavier gloves (16 oz) do not always reduce head acceleration. In men, heavier gloves led to higher loads, likely due to greater punch kinetic energy. In women, the opposite relationship was observed, which may result from reduced hand speed and muscle force under greater load. The load values did not exceed injury threshold levels (according to the WSTC curve), suggesting that single impacts do not cause direct brain damage. However, frequent, repeated microtraumas may lead to structural damage of neural tissue and the accumulation of tau protein, characteristic of chronic traumatic encephalopathy (CTE) [
7].
The overload occurring during the tests was significantly lower than the values presented in the WSTC tolerance curve. In such a situation, a single blow should not result in brain contusion, but one should remember the frequency of blows to the face during a boxing fight. Minor injuries, occurring frequently or systematically, may lead to complications and increase the risk of Parkinsonism or Boxer’s encephalopathy. The accuracy of measurements may still depend on external factors, such as the stability of the measuring equipment, predispositions, and differences in striking technique.
An additional important aspect in protecting the central nervous system is neck injuries. In a 2010 CMAJ article by Kelly Russell, MSc, and Josh Christie, BHSc, over 10 studies were reviewed regarding the effect of helmets on the increased risk of whiplash injuries in winter sports. Based on these studies, there was no association between wearing a helmet and an increased risk of neck injuries, which confirms the safety of helmets [
59,
77,
78]. The protocol and dataset can serve as a screening/benchmarking tool for protective-equipment R&D, highlighting that HIC may remain insensitive under low-to-moderate impacts while angular kinematics change—supporting the routine inclusion of rotational metrics in design verification. The controlled human-delivered setup provides parameters for calibrating mechanical impact rigs and for validating computational models (e.g., finite element method), and it informs design choices that balance mass distribution and damping without assuming that higher mass is protective.
Many articles, scientific papers, and expert opinions on injuries in contact sports agree that education and awareness of the consequences are important factors influencing athletes’ safety. In the Olympic formula, a boxing match lasts 9 min (3 × 3 min), and the average number of blows to the head is 33.4. In contrast, for taekwondo, the fight lasts 6 min (3 × 2 min), and the number of blows to the face is 7.32. Despite the differences related to the rules, scoring system, or motor preparation, both disciplines are burdened with a high risk of injuries, such as a concussion. Much of the technology used in boxing and American football is not available in lesser-known disciplines, which reduces the ability to protect athletes. It should also be emphasized that the regulations specifying the forms of contact and permitted punches are important [
31,
79].